Fair Values of Financial Instruments (Fair Value by Balance Sheet Grouping) (Details) - USD ($)
$ in Thousands |
Dec. 31, 2016 |
Dec. 31, 2015 |
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |
|
|
| Securities held to maturity |
$ 7,337,611
|
$ 7,335,436
|
| Securities available for sale |
3,060,363
|
2,879,583
|
| Derivatives, index options |
120,644
|
38,409
|
| Carrying Values [Member] |
|
|
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |
|
|
| Securities held to maturity |
7,159,259
|
7,173,967
|
| Securities available for sale |
3,060,363
|
2,879,583
|
| Cash and cash equivalents |
51,247
|
106,007
|
| Mortgage loans |
174,534
|
108,311
|
| Policy loans |
58,699
|
61,957
|
| Other loans |
14,343
|
2,779
|
| Derivatives, index options |
120,644
|
38,409
|
| Life interest in Libbie Shearn Moody Trust |
7,550
|
7,379
|
| Deferred annuity contracts |
7,739,337
|
7,640,951
|
| Immediate annuity and supplemental contracts |
443,226
|
434,468
|
| Fair Values |
|
|
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |
|
|
| Securities held to maturity |
7,337,611
|
7,335,436
|
| Securities available for sale |
3,060,363
|
2,879,583
|
| Cash and cash equivalents |
51,247
|
106,007
|
| Mortgage loans |
176,890
|
111,162
|
| Policy loans |
101,092
|
108,550
|
| Other loans |
14,898
|
2,957
|
| Derivatives, index options |
120,644
|
38,409
|
| Life interest in Libbie Shearn Moody Trust |
12,775
|
12,775
|
| Deferred annuity contracts |
7,367,851
|
7,288,108
|
| Immediate annuity and supplemental contracts |
470,414
|
461,457
|
| Level 1 |
|
|
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |
|
|
| Securities held to maturity |
|
0
|
| Securities available for sale |
18,313
|
17,980
|
| Cash and cash equivalents |
51,247
|
106,007
|
| Mortgage loans |
0
|
0
|
| Policy loans |
0
|
0
|
| Other loans |
0
|
0
|
| Derivatives, index options |
0
|
0
|
| Life interest in Libbie Shearn Moody Trust |
0
|
0
|
| Deferred annuity contracts |
0
|
0
|
| Immediate annuity and supplemental contracts |
0
|
0
|
| Level 2 |
|
|
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |
|
|
| Securities held to maturity |
7,337,611
|
7,335,436
|
| Securities available for sale |
3,042,050
|
2,861,603
|
| Cash and cash equivalents |
0
|
0
|
| Mortgage loans |
0
|
0
|
| Policy loans |
0
|
0
|
| Other loans |
0
|
0
|
| Derivatives, index options |
0
|
0
|
| Life interest in Libbie Shearn Moody Trust |
0
|
0
|
| Deferred annuity contracts |
0
|
|
| Immediate annuity and supplemental contracts |
0
|
0
|
| Level 3 |
|
|
| Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |
|
|
| Securities held to maturity |
0
|
0
|
| Securities available for sale |
0
|
0
|
| Cash and cash equivalents |
0
|
0
|
| Mortgage loans |
176,890
|
111,162
|
| Policy loans |
101,092
|
108,550
|
| Other loans |
14,898
|
2,957
|
| Derivatives, index options |
120,644
|
38,409
|
| Life interest in Libbie Shearn Moody Trust |
12,775
|
12,775
|
| Deferred annuity contracts |
7,367,851
|
7,288,108
|
| Immediate annuity and supplemental contracts |
$ 470,414
|
$ 461,457
|