Derivative Instruments (Financial Statement Classification and Impact of Derivatives Used in Qualifying and Non-qualifying Hedge Relationships) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Realized Investment Gains (Losses)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	$ (12,210)	$ (4,266)	$ (672)	$ (5,244)
Net Investment Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	154	(5)	248	(17)
Other Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(10)	(24)	228	(9)
Accumulated Other Comprehensive Income (Loss)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(3,088)	(1,060)	5,236	(423)
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Realized Investment Gains (Losses)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Net Investment Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	154	(5)	248	(17)
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Other Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(13)	(15)	126	(17)
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Accumulated Other Comprehensive Income (Loss)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(3,088)	(1,060)	5,236	(423)
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Currency/Interest Rate | Realized Investment Gains (Losses)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Currency/Interest Rate | Net Investment Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	154	(5)	248	(17)
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Currency/Interest Rate | Other Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(13)	(15)	126	(17)
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Currency/Interest Rate | Accumulated Other Comprehensive Income (Loss)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(3,088)	(1,060)	5,236	(423)
Derivatives Not Qualifying as Hedge Accounting Instruments: | Realized Investment Gains (Losses)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(12,210)	(4,266)	(672)	(5,244)
Derivatives Not Qualifying as Hedge Accounting Instruments: | Net Investment Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Other Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	3	(9)	102	8
Derivatives Not Qualifying as Hedge Accounting Instruments: | Accumulated Other Comprehensive Income (Loss)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Interest Rate | Realized Investment Gains (Losses)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(44,242)	26,012	(14,198)	63,598
Derivatives Not Qualifying as Hedge Accounting Instruments: | Interest Rate | Net Investment Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Interest Rate | Other Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Interest Rate | Accumulated Other Comprehensive Income (Loss)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency | Realized Investment Gains (Losses)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	18	0	18	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency | Net Investment Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency | Other Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency | Accumulated Other Comprehensive Income (Loss)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency/Interest Rate | Realized Investment Gains (Losses)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(790)	(1,038)	5,216	(214)
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency/Interest Rate | Net Investment Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency/Interest Rate | Other Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	3	(9)	102	8
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency/Interest Rate | Accumulated Other Comprehensive Income (Loss)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Credit | Realized Investment Gains (Losses)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(1)	(4)	(2)	(11)
Derivatives Not Qualifying as Hedge Accounting Instruments: | Credit | Net Investment Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Credit | Other Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Credit | Accumulated Other Comprehensive Income (Loss)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Equity | Realized Investment Gains (Losses)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(990)	(11,334)	(4,873)	(15,982)
Derivatives Not Qualifying as Hedge Accounting Instruments: | Equity | Net Investment Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Equity | Other Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Equity | Accumulated Other Comprehensive Income (Loss)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Embedded Derivatives | Realized Investment Gains (Losses)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	33,795	(17,902)	13,167	(52,635)
Derivatives Not Qualifying as Hedge Accounting Instruments: | Embedded Derivatives | Net Investment Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Embedded Derivatives | Other Income
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Embedded Derivatives | Accumulated Other Comprehensive Income (Loss)
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	$ 0	$ 0	$ 0	$ 0