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, gain (loss) on derivatives, net	$ (172,883)	$ 27,443	$ (116,162)	$ 111,565
Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	711	264	1,248	517
Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(1,384)	(347)	15	(404)
Accumulated Other Comprehensive Income (Loss)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(11,795)	(2,500)	12,901	(2,392)
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Realized Investment Gains/(Losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0	0	0	0
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	711	264	1,248	517
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(1,347)	(329)	(83)	(400)
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Accumulated Other Comprehensive Income (Loss)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(11,795)	(2,500)	12,901	(2,392)
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Currency/Interest Rate | Realized Investment Gains/(Losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, 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, gain (loss) on derivatives, net	711	264	1,248	517
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Currency/Interest Rate | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(1,347)	(329)	(83)	(400)
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Currency/Interest Rate | Accumulated Other Comprehensive Income (Loss)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(11,795)	(2,500)	12,901	(2,392)
Derivatives Not Qualifying as Hedge Accounting Instruments: | Realized Investment Gains/(Losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(172,883)	27,443	(116,162)	111,565
Derivatives Not Qualifying as Hedge Accounting Instruments: | Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(37)	(18)	98	(4)
Derivatives Not Qualifying as Hedge Accounting Instruments: | Accumulated Other Comprehensive Income (Loss)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, 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, gain (loss) on derivatives, net	(164,405)	70,929	(49,273)	162,506
Derivatives Not Qualifying as Hedge Accounting Instruments: | Interest Rate | Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Interest Rate | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, 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, gain (loss) on derivatives, net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency | Realized Investment Gains/(Losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(84)	(17)	52	(14)
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency | Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, 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, gain (loss) on derivatives, 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, gain (loss) on derivatives, net	(3,715)	(273)	4,551	654
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency/Interest Rate | Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency/Interest Rate | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(37)	(18)	98	(4)
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency/Interest Rate | Accumulated Other Comprehensive Income (Loss)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Credit | Realized Investment Gains/(Losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(88)	(116)	(163)	(158)
Derivatives Not Qualifying as Hedge Accounting Instruments: | Credit | Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Credit | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, 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, gain (loss) on derivatives, net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Equity | Realized Investment Gains/(Losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(5,845)	(26,232)	(21,170)	(34,315)
Derivatives Not Qualifying as Hedge Accounting Instruments: | Equity | Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Equity | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, 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, gain (loss) on derivatives, 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, gain (loss) on derivatives, net	1,254	(16,848)	(50,159)	(17,108)
Derivatives Not Qualifying as Hedge Accounting Instruments: | Embedded Derivatives | Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0	0	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Embedded Derivatives | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, 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, gain (loss) on derivatives, net	$ 0	$ 0	$ 0	$ 0