Fair Value of Assets and Liabilities (Level 3 by Pricing Source) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Separate account assets	$ 109,350,121	$ 109,194,192
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other long-term investments	73,873	29,572
Reinsurance recoverables	4,940,011	4,897,545
Receivables from parent and affiliates	162,625	177,672
Subtotal excluding separate account assets	12,383,757	11,567,629
Separate account assets	109,350,121	109,194,192
Total assets	121,733,878	120,761,821
Future policy benefits	5,205,434	4,993,611
Total liabilities	5,205,434	4,993,611
Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	18,413	6,290
Other long-term investments	7,033	2,115
Reinsurance recoverables	4,940,011	4,897,545
Receivables from parent and affiliates	5,000	19,203
Subtotal excluding separate account assets	5,239,296	5,110,171
Separate account assets	382,959	302,924
Total assets	5,622,255	5,413,095
Future policy benefits	5,205,434	4,993,611
Total liabilities	5,205,434	4,993,611
Level 3 | Fair Value, Measurements, Recurring | Separate account assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Separate account assets	382,959	302,924
Level 3 | Fair Value, Measurements, Recurring | Internal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	165	750
Other long-term investments	3,260	565
Reinsurance recoverables	4,940,011	4,897,545
Receivables from parent and affiliates	0	0
Subtotal excluding separate account assets	4,984,086	4,922,836
Total assets	5,072,134	5,006,947
Future policy benefits	5,205,434	4,993,611
Total liabilities	5,205,434	4,993,611
Level 3 | Fair Value, Measurements, Recurring | Internal | Separate account assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Separate account assets	88,048	84,111
Level 3 | Fair Value, Measurements, Recurring | External
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	18,248	5,540
Other long-term investments	3,773	1,550
Reinsurance recoverables	0	0
Receivables from parent and affiliates	5,000	19,203
Subtotal excluding separate account assets	255,210	187,335
Total assets	550,121	406,148
Future policy benefits	0	0
Total liabilities	0	0
Level 3 | Fair Value, Measurements, Recurring | External | Separate account assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Separate account assets	294,911	218,813
Level 3 | Corporate securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate and Asset-backed securities	95,492	84,801
Level 3 | Corporate securities | Fair Value, Measurements, Recurring | Internal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate and Asset-backed securities	40,492	23,712
Level 3 | Corporate securities | Fair Value, Measurements, Recurring | External
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate and Asset-backed securities	55,000	61,089
Level 3 | Asset-backed securities | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate and Asset-backed securities	173,347	100,217
Level 3 | Asset-backed securities | Fair Value, Measurements, Recurring | Internal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate and Asset-backed securities	158	264
Level 3 | Asset-backed securities | Fair Value, Measurements, Recurring | External
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate and Asset-backed securities	$ 173,189	$ 99,953