Derivative Instruments (Financial Statement Classification and Impact of Derivatives Used in Qualifying and Non-qualifying Hedge Relationships) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Realized Investment Gains/(Losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	$ 69,647	$ 56,720
Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	1,405	537
Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(1,909)	1,399
AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(17,099)	24,696
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
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	1,405	537
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(1,899)	1,264
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(17,099)	24,696
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
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	1,405	537
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	(1,899)	1,264
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Currency/Interest Rate | AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(17,099)	24,696
Derivatives Not Qualifying as Hedge Accounting Instruments: | Realized Investment Gains/(Losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	69,647	56,720
Derivatives Not Qualifying as Hedge Accounting Instruments: | Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(10)	135
Derivatives Not Qualifying as Hedge Accounting Instruments: | AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	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	189,927	115,132
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
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
Derivatives Not Qualifying as Hedge Accounting Instruments: | Interest Rate | AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	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	(126)	136
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
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency | AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	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	(1,095)	8,265
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
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency/Interest Rate | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(10)	135
Derivatives Not Qualifying as Hedge Accounting Instruments: | Currency/Interest Rate | AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	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	(241)	(75)
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
Derivatives Not Qualifying as Hedge Accounting Instruments: | Credit | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Credit | AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	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	(3,314)	(15,324)
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
Derivatives Not Qualifying as Hedge Accounting Instruments: | Equity | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Equity | AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	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	(115,504)	(51,414)
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
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
Derivatives Not Qualifying as Hedge Accounting Instruments: | Embedded Derivatives | AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	$ 0	$ 0