Pension Plans, Noncontributory Defined-Benefit Pension Plan (Details) - USD ($)
$ in Thousands |
12 Months Ended |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Summary of amounts recognized in the balance sheets [Abstract] |
|
|
|
| Accumulated other comprehensive loss, deferred tax |
$ 7,191
|
$ 17,500
|
|
| Components of net periodic benefit cost [Abstract] |
|
|
|
| Settlement charges |
0
|
0
|
|
| Summary of estimated net loss and prior service benefit that will be amortized from accumulated other comprehensive loss into net periodic pension benefits cost during the next twelve months [Abstract] |
|
|
|
| Estimated net actuarial loss that will be amortized from accumulated other comprehensive loss into net periodic pension benefits cost during the next twelve months |
$ 345
|
|
|
| Noncontributory Defined-Benefit Pension Plan [Member] |
|
|
|
| Defined Benefit Plan Disclosure [Line Items] |
|
|
|
| Requisite service period |
5 years
|
|
|
| Change in benefit obligation [Roll Forward] |
|
|
|
| Benefit obligation at beginning of year |
$ 184,782
|
205,254
|
|
| Service cost |
3,640
|
4,137
|
$ 3,589
|
| Interest cost |
8,749
|
8,281
|
8,287
|
| Benefit payments |
(12,911)
|
(7,591)
|
|
| Actuarial (gain) loss |
14,709
|
(25,299)
|
|
| Liability gain due to curtailment |
(35,092)
|
0
|
|
| Benefit obligation at end of year |
163,877
|
184,782
|
205,254
|
| Accumulated benefit obligation at end of year |
163,877
|
152,851
|
|
| Change in fair value of plan assets [Roll Forward] |
|
|
|
| Fair value of plan assets at beginning of year |
130,061
|
128,108
|
|
| Actual return on assets |
13,248
|
1,544
|
|
| Employer contributions |
10,000
|
8,000
|
|
| Benefit payments |
(12,911)
|
(7,591)
|
|
| Fair value of plan assets at end of year |
140,398
|
130,061
|
128,108
|
| Funded status at end of year |
(23,479)
|
(54,721)
|
|
| Amounts in accumulated other comprehensive income not yet recognized as a component of net periodic pension cost [Abstract] |
|
|
|
| Development of prior service credit, Balance at beginning of year |
(2,223)
|
(2,673)
|
|
| Amortization |
450
|
450
|
450
|
| Curtailment/Settlement |
1,773
|
0
|
|
| Net prior service credit |
0
|
(2,223)
|
(2,673)
|
| Development of actuarial loss, Balance at beginning of year |
55,716
|
80,118
|
|
| Amortization |
(4,028)
|
(5,939)
|
(4,134)
|
| (Gain)/Loss arising during the year |
10,464
|
(18,463)
|
|
| Curtailment/Settlement gain during the year |
(35,092)
|
0
|
|
| Actuarial net loss |
27,060
|
55,716
|
80,118
|
| Sum of deferrals |
27,060
|
53,493
|
|
| Net amount recognized |
$ 3,581
|
$ (1,228)
|
|
| Weighted average basis on benefits obligations [Abstract] |
|
|
|
| Discount rate |
4.50%
|
4.75%
|
|
| Summary of amounts recognized in the balance sheets [Abstract] |
|
|
|
| Pension liability |
$ 23,479
|
$ 54,721
|
|
| Accumulated other comprehensive loss, net of a deferred tax of $7,191 and $17,500 in 2016 and 2015, respectively |
19,869
|
35,993
|
|
| Components of net periodic benefit cost [Abstract] |
|
|
|
| Service cost |
3,640
|
4,137
|
3,589
|
| Interest cost |
8,749
|
8,281
|
8,287
|
| Expected return on assets |
(9,003)
|
(8,380)
|
(7,496)
|
| Prior service benefit |
(450)
|
(450)
|
(450)
|
| Actuarial loss |
4,028
|
5,939
|
4,134
|
| Net periodic benefit cost |
$ 6,964
|
$ 9,527
|
$ 8,064
|
| Weighted average basis on periodic benefit cost [Abstract] |
|
|
|
| Discount rate |
4.75%
|
4.25%
|
5.25%
|
| Expected return on plan assets |
7.00%
|
7.00%
|
7.00%
|
| Period over which annual rates of return are projected under target asset allocation |
30 years
|
|
|
| Expected rate of return on plan assets |
7.00%
|
7.00%
|
|
| Reduction in other administrative expenses |
0.15%
|
|
|
| Noncontributory Defined-Benefit Pension Plan [Member] | Minimum [Member] |
|
|
|
| Weighted average basis on benefits obligations [Abstract] |
|
|
|
| Rate of compensation increase |
|
3.50%
|
|
| Weighted average basis on periodic benefit cost [Abstract] |
|
|
|
| Rate of compensation increase |
3.50%
|
3.50%
|
3.50%
|
| Percentile range of assets allocation |
35.00%
|
|
|
| Expected rate of return on plan assets |
5.70%
|
|
|
| Noncontributory Defined-Benefit Pension Plan [Member] | Maximum [Member] |
|
|
|
| Weighted average basis on benefits obligations [Abstract] |
|
|
|
| Rate of compensation increase |
|
8.00%
|
|
| Weighted average basis on periodic benefit cost [Abstract] |
|
|
|
| Rate of compensation increase |
8.00%
|
8.00%
|
8.00%
|
| Percentile range of assets allocation |
65.00%
|
|
|
| Expected rate of return on plan assets |
7.10%
|
|
|
| Noncontributory Defined-Benefit Pension Plan [Member] | Equity Securities [Member] |
|
|
|
| Weighted average basis on periodic benefit cost [Abstract] |
|
|
|
| Target asset allocation minimum |
44.00%
|
|
|
| Target asset allocation maximum |
56.00%
|
|
|
| Noncontributory Defined-Benefit Pension Plan [Member] | Debt Securities [Member] |
|
|
|
| Weighted average basis on periodic benefit cost [Abstract] |
|
|
|
| Target asset allocation minimum |
34.00%
|
|
|
| Target asset allocation maximum |
46.00%
|
|
|
| Noncontributory Defined-Benefit Pension Plan [Member] | Other Securities [Member] |
|
|
|
| Weighted average basis on periodic benefit cost [Abstract] |
|
|
|
| Target asset allocation minimum |
6.00%
|
|
|
| Target asset allocation maximum |
14.00%
|
|
|