Employee Benefits (Tables)
 12 Months Ended
Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]  
Schedule of Significant Unobservable Inputs
Presented in the tables below are a reconciliation of the beginning and ending balances of the fair value measurements using significant unobservable inputs (Level 3) for 2019 and 2018, respectively:
 
Level 3
Balance as of January 1, 2019
$
230

Actual return on assets
25

Purchases, issuances and settlements, net
94

Balance as of December 31, 2019
$
349

 
Level 3
Balance as of January 1, 2018
$
278

Actual return on assets
(23
)
Purchases, issuances and settlements, net
(25
)
Balance as of December 31, 2018
$
230
Schedule of Rollforward Changes in Benefit Obligation and Plan Assets
Presented in the table below is a rollforward of the changes in the benefit obligation and plan assets for the two most recent years, for all plans combined:
 
Pension Benefits
 
Other Benefits
 
2019
 
2018
 
2019
 
2018
Change in benefit obligation:
 
 
 
 
 
 
 
Benefit obligation as of January 1,
$
1,892

 
$
2,034

 
$
353

 
$
614

Service cost
28

 
34

 
4

 
8

Interest cost
82

 
76

 
15

 
20

Plan participants' contributions
—

 
—

 
2

 
2

Plan amendments
—

 
(23
)
 
(1
)
 
(174
)
Actuarial loss (gain)
264

 
(153
)
 
25

 
(89
)
Gross benefits paid
(105
)
 
(76
)
 
(25
)
 
(29
)
Federal subsidy
—

 
—

 
1

 
1

Benefit obligation as of December 31,
$
2,161

 
$
1,892

 
$
374

 
$
353

Change in plan assets:
 
 
 
 
 
 
 
Fair value of plan assets as of January 1,
$
1,499

 
$
1,649

 
$
507

 
$
576

Actual return on plan assets
319

 
(97
)
 
51

 
(40
)
Employer contributions
33

 
24

 
(2
)
 
(2
)
Plan participants' contributions
—

 
—

 
2

 
2

Benefits paid
(104
)
 
(77
)
 
(26
)
 
(29
)
Fair value of plan assets as of December 31,
$
1,747

 
$
1,499

 
$
532

 
$
507

Funded value as of December 31,
$
(414
)
 
$
(393
)
 
$
158

 
$
154

Amounts recognized on the balance sheet:
 
 
 
 
 
 
 
Noncurrent asset
$
—

 
$
—

 
$
159

 
$
155

Current liability
(3
)
 
(3
)
 
—

 
—

Noncurrent liability
(411
)
 
(390
)
 
(1
)
 
(1
)
Net amount recognized
$
(414
)
 
$
(393
)
 
$
158

 
$
154
Summary of Accumulated Other Comprehensive Income and Regulatory Assets
Presented in the table below are the components of accumulated other comprehensive income and regulatory assets that have not been recognized as components of periodic benefit costs as of December 31:
 
Pension Benefits
 
Other Benefits
 
2019
 
2018
 
2019
 
2018
Net actuarial loss
$
435

 
$
431

 
$
72

 
$
83

Prior service credit
(19
)
 
(22
)
 
(257
)
 
(291
)
Net amount recognized
$
416

 
$
409

 
$
(185
)
 
$
(208
)
 
 
 
 
 
 
 
 
Regulatory assets (liabilities)
$
375

 
$
352

 
$
(185
)
 
$
(208
)
Accumulated other comprehensive income
41

 
57

 
—

 
—

Total
$
416

 
$
409

 
$
(185
)
 
$
(208
)
Schedule of Projected Benefit Obligation, Accumulated Benefit Obligation and Fair Value of Plan Assets
Presented in the tables below are the projected benefit obligation, accumulated benefit obligation and fair value of plan assets for pension plans with a projected obligation in excess of plan assets as of December 31, 2019 and 2018:
 
Projected Benefit Obligation Exceeds the Fair Value of Plans' Assets
 
2019
 
2018
Projected benefit obligation
$
2,161

 
$
1,892

Fair value of plan assets
1,748

 
1,499

 
 
 
 
 
Accumulated Benefit Obligation Exceeds the Fair Value of Plans' Assets
 
2019
 
2018
Accumulated benefit obligation
$
2,018

 
$
1,768

Fair value of plan assets
1,748

 
1,499
Schedule of Expected Cash Flows for Pension and Postretirement Benefit Plans
Presented in the table below is information about the expected cash flows for the pension and postretirement benefit plans:
 
Pension Benefits
 
Other Benefits
2020 expected employer contributions:
 
 
 
To plan trusts
$
38

 
$
—

To plan participants
2

 
—
Schedule of Expected Benefit Payments
Presented in the table below are the net benefits expected to be paid from the plan assets or the Company’s assets:
 
Pension Benefits
 
Other Benefits
 
Expected Benefit Payments
 
Expected Benefit Payments
 
Expected Federal Subsidy Payments
2020
$
113

 
$
27

 
$
1

2021
115

 
27

 
1

2022
118

 
27

 
1

2023
123

 
27

 
1

2024
126

 
27

 
1

2025-2029
657

 
131

 
6
Schedule of Significant Assumptions of Pension and Other Postretirement Benefit Plans
Presented in the table below are the significant assumptions related to the pension and other postretirement benefit plans:
 
Pension Benefits
 
Other Benefits
 
2019
 
2018
 
2017
 
2019
 
2018
 
2017
Weighted average assumptions used to determine December 31 benefit obligations:
 
 
 
 
 
 
 
 
 
 
 
Discount rate
3.44%
 
4.38%
 
3.75%
 
3.36%
 
4.32%
 
3.73%
Rate of compensation increase
2.97%
 
3.00%
 
3.02%
 
N/A
 
N/A
 
N/A
Medical trend
N/A
 
N/A
 
N/A
 
graded from
 
graded from
 
graded from
 
 
 
 
 
 
 
6.50% in 2020
 
6.75% in 2019
 
7.00% in 2018
 
 
 
 
 
 
 
to 5.00% in 2026+
 
to 5.00% in 2026+
 
to 4.50% in 2026+
Weighted average assumptions used to determine net periodic cost:
 
 
 
 
 
 
 
 
 
 
 
Discount rate
4.38%
 
3.75%
 
4.28%
 
4.32%
 
4.23%
 
4.26%
Expected return on plan assets
6.20%
 
5.95%
 
6.49%
 
3.56%
 
4.77%
 
5.09%
Rate of compensation increase
3.00%
 
3.02%
 
3.07%
 
N/A
 
N/A
 
N/A
Medical trend
N/A
 
N/A
 
N/A
 
graded from
 
graded from
 
graded from
 
 
 
 
 
 
 
6.75% in 2019
 
7.00% in 2018
 
7.00% in 2017
 
 
 
 
 
 
 
to 5.00% in 2026+
 
to 4.50% in 2026+
 
to 5.00% in 2021+
NOTE
“N/A” in the table above means assumption is not applicable.
Components of Net Periodic Benefit Costs
Presented in the table below are the components of net periodic benefit costs for the years ended December 31:
 
2019
 
2018
 
2017
Components of net periodic pension benefit cost:
 
 
 
 
 
Service cost
$
28

 
$
34

 
$
33

Interest cost
82

 
76

 
80

Expected return on plan assets
(91
)
 
(97
)
 
(93
)
Amortization of prior service (credit) cost
(3
)
 
1

 
1

Amortization of actuarial loss
32

 
27

 
34

Net periodic pension benefit cost
$
48

 
$
41

 
$
55

Other changes in plan assets and benefit obligations recognized in other comprehensive income:
 
 
 
 
 
Current year actuarial (gain) loss
$
(8
)
 
$
(60
)
 
$
(7
)
Amortization of actuarial loss
(4
)
 
(7
)
 
(7
)
Total recognized in other comprehensive income
(12
)
 
(67
)
 
(14
)
Total recognized in net periodic benefit cost and other comprehensive income
$
36

 
$
(26
)
 
$
41

Components of net periodic other postretirement benefit (credit) cost:
 
 
 
 
 
Service cost
$
4

 
$
8

 
$
10

Interest cost
15

 
20

 
26

Expected return on plan assets
(18
)
 
(26
)
 
(26
)
Amortization of prior service credit
(35
)
 
(23
)
 
(18
)
Amortization of actuarial loss
3

 
3

 
10

Net periodic other postretirement benefit (credit) cost
$
(31
)
 
$
(18
)
 
$
2
Pension Plan Asset  
Defined Benefit Plan Disclosure [Line Items]  
Schedule of Changes in Fair Value of Plan Assets
Presented in the tables below are the fair values and asset allocations of the pension plan assets as of December 31, 2019 and 2018, respectively, by asset category:
Asset Category
 
2020 Target Allocation
 
Total
 
Quoted Prices in Active Markets for Identical Assets (Level 1)
 
Significant Observable Inputs (Level 2)
 
Significant Unobservable Inputs (Level 3)
 
Percentage of Plan Assets as of December 31, 2019
Cash
 
 
 
$
39

 
$
39

 
$
—

 
$
—

 
2
%
Equity securities:
 
50
%
 
 
 
 
 
 
 
 
 
 
U.S. large cap
 
 
 
358

 
358

 
—

 
—

 
20
%
U.S. small cap
 
 
 
84

 
78

 
6

 
—

 
5
%
International
 
 
 
320

 
6

 
137

 
177

 
18
%
Real estate fund
 
 
 
127

 
—

 
—

 
127

 
7
%
REITs
 
 
 
7

 
—

 
7

 
—

 
—
%
Fixed income securities:
 
50
%
 
 
 
 
 
 
 
 
 
 
U.S. Treasury securities and government bonds
 
 
 
169

 
158

 
11

 
—

 
10
%
Corporate bonds
 
 
 
542

 
—

 
542

 
—

 
31
%
Mortgage-backed securities
 
 
 
14

 
—

 
14

 
—

 
1
%
Municipal bonds
 
 
 
26

 
—

 
26

 
—

 
1
%
Treasury futures
 
 
 
8

 
8

 
—

 
—

 
1
%
Long duration bond fund
 
 
 
8

 
8

 
—

 
—

 
1
%
Guarantee annuity contracts
 
 
 
45

 
—

 
—

 
45

 
3
%
Total
 
100
%
 
$
1,747

 
$
655

 
$
743

 
$
349

 
100
%
Asset Category
 
2019 Target Allocation
 
Total
 
Quoted Prices in Active Markets for Identical Assets (Level 1)
 
Significant Observable Inputs (Level 2)
 
Significant Unobservable Inputs (Level 3)
 
Percentage of Plan Assets as of December 31, 2018
Cash
 
 
 
$
24

 
$
24

 
$
—

 
$
—

 
2
%
Equity securities:
 
50
%
 
 
 
 
 
 
 
 
 
 
U.S. large cap
 
 
 
297

 
297

 
—

 
—

 
20
%
U.S. small cap
 
 
 
76

 
70

 
6

 
—

 
5
%
International
 
 
 
256

 
2

 
132

 
122

 
17
%
Real estate fund
 
 
 
65

 
—

 
—

 
65

 
4
%
REITs
 
 
 
20

 
—

 
20

 
—

 
1
%
Fixed income securities:
 
50
%
 
 
 
 
 
 
 
 
 
 
U.S. Treasury securities and government bonds
 
 
 
181

 
167

 
14

 
—

 
12
%
Corporate bonds
 
 
 
491

 
—

 
491

 
—

 
33
%
Mortgage-backed securities
 
 
 
11

 
—

 
11

 
—

 
1
%
Municipal bonds
 
 
 
28

 
—

 
28

 
—

 
2
%
Long duration bond fund
 
 
 
7

 
7

 
—

 
—

 
—
%
Guarantee annuity contracts
 
 
 
43

 
—

 
—

 
43

 
3
%
Total
 
100
%
 
$
1,499

 
$
567

 
$
702

 
$
230

 
100
%
Postretirement Benefit Plan Assets  
Defined Benefit Plan Disclosure [Line Items]  
Schedule of Changes in Fair Value of Plan Assets
Presented in the tables below are the fair values and asset allocations of the postretirement benefit plan assets as of December 31, 2019 and 2018, respectively, by asset category:
Asset Category
 
2020 Target Allocation
 
Total
 
Quoted Prices in Active Markets for Identical Assets (Level 1)
 
Significant Observable Inputs (Level 2)
 
Significant Unobservable Inputs (Level 3)
 
Percentage of Plan Assets as of December 31, 2019
Bargain VEBA:
 
 
 
 
 
 
 
 
 
 
 
 
Cash
 
 
 
$
6

 
$
6

 
$
—

 
$
—

 
2
%
Equity securities:
 
4
%
 
 
 
 
 
 
 
 
 
 
U.S. large cap
 
 
 
13

 
13

 
—

 
—

 
3
%
Fixed income securities:
 
96
%
 
 
 
 
 
 
 
 
 
 
U.S. Treasury securities and government bonds
 
 
 
373

 
298

 
75

 
—

 
94
%
Long duration bond fund
 
 
 
4

 
4

 
—

 
—

 
1
%
Total bargain VEBA
 
100
%
 
$
396

 
$
321

 
$
75

 
$
—

 
100
%
Non-bargain VEBA:
 
 
 
 
 
 
 
 
 
 
 
 
Cash
 
 
 
$
4

 
$
4

 
$
—

 
$
—

 
—

Equity securities:
 
60
%
 
 
 
 
 
 
 
 
 
 
U.S. large cap
 
 
 
48

 
48

 
—

 
—

 
36
%
International
 
 
 
30

 
30

 
—

 
—

 
23
%
Fixed income securities:
 
40
%
 
 
 
 
 
 
 
 
 
 
Core fixed income bond fund (a)
 
 
 
50

 
—

 
50

 
—

 
41
%
Total non-bargain VEBA
 
100
%
 
$
132

 
$
82

 
$
50

 
$
—

 
100
%
Life VEBA:
 
 
 
 
 
 
 
 
 
 
 
 
Equity securities:
 
70
%
 
 
 
 
 
 
 
 
 
 
U.S. large cap
 
 
 
$
2

 
$
2

 
$
—

 
$
—

 
50
%
Fixed income securities:
 
30
%
 
 
 
 
 
 
 
 
 
 
Core fixed income bond fund (a)
 
 
 
2

 
2

 
—

 
—

 
50
%
Total life VEBA
 
100
%
 
$
4

 
$
4

 
$
—

 
$
—

 
100
%
Total
 
100
%
 
$
532

 
$
407

 
$
125

 
$
—

 
100
%
 
(a)
Includes cash for margin requirements.
Asset Category
 
2019 Target Allocation
 
Total
 
Quoted Prices in Active Markets for Identical Assets (Level 1)
 
Significant Observable Inputs (Level 2)
 
Significant Unobservable Inputs (Level 3)
 
Percentage of Plan Assets as of 12/31/2018
Bargain VEBA:
 
 
 
 
 
 
 
 
 
 
 
 
Cash
 
 
 
$
31

 
$
31

 
$
—

 
$
—

 
—

Equity securities:
 
2
%
 
 
 
 
 
 
 
 
 
 
U.S. large cap
 
 
 
1

 
1

 
—

 
—

 
—
%
International
 
 
 
17

 
—

 
—

 
17

 
4
%
Fixed income securities:
 
98
%
 
 
 
 
 
 
 
 
 
 
U.S. Treasury securities and government bonds
 
 
 
179

 
178

 
1

 
—

 
47
%
Corporate bonds
 
 
 
141

 
—

 
141

 
—

 
37
%
Municipal bonds
 
 
 
9

 
—

 
9

 
—

 
3
%
Long duration bond fund
 
 
 
4

 
4

 
—

 
—

 
1
%
Future and option contracts (a)
 
 
 
—

 
—

 
—

 
—

 
8
%
Total bargain VEBA
 
100
%
 
$
382

 
$
214

 
$
151

 
$
17

 
100
%
Non-bargain VEBA:
 
 
 
 
 
 
 
 
 
 
 
 
Cash
 
 
 
$
3

 
$
3

 
$
—

 
$
—

 
—

Equity securities:
 
60
%
 
 
 
 
 
 
 
 
 
 
U.S. large cap
 
 
 
43

 
43

 
—

 
—

 
35
%
International
 
 
 
24

 
24

 
—

 
—

 
20
%
Fixed income securities:
 
40
%
 
 
 
 
 
 
 
 
 
 
Core fixed income bond fund (a)
 
 
 
52

 
—

 
52

 
—

 
45
%
Total non-bargain VEBA
 
100
%
 
$
122

 
$
70

 
$
52

 
$
—

 
100
%
Life VEBA:
 
 
 
 
 
 
 
 
 
 
 
 
Equity securities:
 
70
%
 
 
 
 
 
 
 
 
 
 
U.S. large cap
 
 
 
$
2

 
$
2

 
$
—

 
$
—

 
67
%
Fixed income securities:
 
30
%
 
 
 
 
 
 
 
 
 
 
Core fixed income bond fund (a)
 
 
 
1

 
1

 
—

 
—

 
33
%
Total life VEBA
 
100
%
 
$
3

 
$
3

 
$
—

 
$
—

 
100
%
Total
 
100
%
 
$
507

 
$
287

 
$
203

 
$
17

 
100
%
(a)
Includes cash for margin requirements.