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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Realized Investment Gains (Losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	$ (76,353)	$ (49,846)	$ 17,104	$ (94,323)
Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	2,746	2,211	5,372	4,280
Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(3,697)	1,486	5,189	(29)
AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(30,329)	13,316	67,741	6,662
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	387	(88)	727	(248)
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	2,746	2,211	5,372	4,280
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(3,687)	1,482	5,141	(34)
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(30,329)	13,316	67,741	6,662
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Interest Rate | Realized Investment Gains (Losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0		(44)
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Interest Rate | Net Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	1		(2)
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Interest Rate | Other Income
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	0		0
Derivatives Designated as Hedge Accounting Instruments: | Cash flow hedges | Interest Rate | AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	27		327
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	387	(88)	771	(248)
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	2,745	2,211	5,374	4,280
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	(3,687)	1,482	5,141	(34)
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	(30,356)	13,316	67,414	6,662
Derivatives Not Qualifying as Hedge Accounting Instruments: | Realized Investment Gains (Losses)
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	(76,740)	(49,758)	16,377	(94,075)
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	(10)	4	48	5
Derivatives Not Qualifying as Hedge Accounting Instruments: | AOCI
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	(796)	7,682	29,709	15,297
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 | AOCI
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	(444)	343	1,027	323
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 | AOCI
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	(4,662)	1,673	14,671	3,103
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	(10)	4	48	5
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	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	(225)	0	(225)	(1)
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 | AOCI
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	42,826	12,666	(32,118)	41,529
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 | AOCI
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	(113,439)	(72,122)	3,313	(154,326)
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 | AOCI
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss) on derivatives, net	$ 0	$ 0	$ 0	$ 0