Investments (Components of Investment Income) (Details) - USD ($)
$ in Thousands |
12 Months Ended |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Schedule of Investment Income, Reported Amounts, by Category [Line Items] |
|
|
|
| Total investment income |
$ 468,766
|
$ 380,231
|
$ 506,516
|
| Less investment expenses |
1,092
|
1,117
|
1,086
|
| Net investment income |
467,674
|
379,114
|
505,430
|
| Non-income producing |
|
|
|
| Schedule of Investment Income, Reported Amounts, by Category [Line Items] |
|
|
|
| Real estate investment |
200
|
900
|
900
|
| Debt and equity securities |
|
|
|
| Schedule of Investment Income, Reported Amounts, by Category [Line Items] |
|
|
|
| Total investment income |
416,638
|
416,633
|
410,809
|
| Mortgage loans |
|
|
|
| Schedule of Investment Income, Reported Amounts, by Category [Line Items] |
|
|
|
| Total investment income |
7,964
|
10,274
|
9,847
|
| Policy loans |
|
|
|
| Schedule of Investment Income, Reported Amounts, by Category [Line Items] |
|
|
|
| Total investment income |
3,700
|
3,938
|
4,252
|
| Derivative gains (losses) |
|
|
|
| Schedule of Investment Income, Reported Amounts, by Category [Line Items] |
|
|
|
| Total investment income |
28,364
|
(61,750)
|
68,616
|
| Money market investments |
|
|
|
| Schedule of Investment Income, Reported Amounts, by Category [Line Items] |
|
|
|
| Total investment income |
668
|
197
|
401
|
| Other investment income |
|
|
|
| Schedule of Investment Income, Reported Amounts, by Category [Line Items] |
|
|
|
| Total investment income |
$ 11,432
|
$ 10,939
|
$ 12,591
|