Derivative Instruments (Financial Statement Classification and Impact of Derivatives Used in Qualifying and Non-qualifying Hedge Relationships) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net					$ (568)
Net Realized Investments Gain Loss [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(62,913)		46,731		(77,589)		24,451
Net Investment Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(33)		(31)		(107)		(70)
Other Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(11)		23		50		(28)
Accumulated Other Comprehensive Income (loss) [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net	(1,556)	[1]	2,860	[1]	(494)	[1]	1,122	[1]
Cash Flow Hedging [Member] | Net Realized Investments Gain Loss [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0		0		0		0
Cash Flow Hedging [Member] | Net Investment Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(33)		(31)		(107)		(70)
Cash Flow Hedging [Member] | Other Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(4)		23		30		(28)
Cash Flow Hedging [Member] | Accumulated Other Comprehensive Income (loss) [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net	(1,556)	[1]	2,860	[1]	(494)	[1]	1,122	[1]
Cash Flow Hedging [Member] | Cross Currency Interest Rate Contract [Member] | Net Realized Investments Gain Loss [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0		0		0		0
Cash Flow Hedging [Member] | Cross Currency Interest Rate Contract [Member] | Net Investment Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(33)		(31)		(107)		(70)
Cash Flow Hedging [Member] | Cross Currency Interest Rate Contract [Member] | Other Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(4)		23		30		(28)
Cash Flow Hedging [Member] | Cross Currency Interest Rate Contract [Member] | Accumulated Other Comprehensive Income (loss) [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net	(1,556)	[1]	2,860	[1]	(494)	[1]	1,122	[1]
Nondesignated [Member] | Net Realized Investments Gain Loss [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(62,913)		46,731		(77,589)		24,451
Nondesignated [Member] | Net Investment Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0		0		0		0
Nondesignated [Member] | Other Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(7)		0		20		0
Nondesignated [Member] | Accumulated Other Comprehensive Income (loss) [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net	0	[1]	0	[1]	0	[1]	0	[1]
Nondesignated [Member] | Interest Rate Contract [Member] | Net Realized Investments Gain Loss [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(2,942)		88,278		22,912		103,706
Nondesignated [Member] | Interest Rate Contract [Member] | Net Investment Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0		0		0		0
Nondesignated [Member] | Interest Rate Contract [Member] | Other Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0		0		0		0
Nondesignated [Member] | Interest Rate Contract [Member] | Accumulated Other Comprehensive Income (loss) [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net	0	[1]	0	[1]	0	[1]	0	[1]
Nondesignated [Member] | Cross Currency Interest Rate Contract [Member] | Net Realized Investments Gain Loss [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(1,446)		5,251		(296)		2,456
Nondesignated [Member] | Cross Currency Interest Rate Contract [Member] | Net Investment Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0		0		0		0
Nondesignated [Member] | Cross Currency Interest Rate Contract [Member] | Other Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(7)		0		20		0
Nondesignated [Member] | Cross Currency Interest Rate Contract [Member] | Accumulated Other Comprehensive Income (loss) [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net	0	[1]	0	[1]	0	[1]	0	[1]
Nondesignated [Member] | Credit Risk Contract [Member] | Net Realized Investments Gain Loss [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(53)		544		140		1,155
Nondesignated [Member] | Credit Risk Contract [Member] | Net Investment Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0		0		0		0
Nondesignated [Member] | Credit Risk Contract [Member] | Other Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0		0		0		0
Nondesignated [Member] | Credit Risk Contract [Member] | Accumulated Other Comprehensive Income (loss) [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net	0	[1]	0	[1]	0	[1]	0	[1]
Nondesignated [Member] | Equity Contract [Member] | Net Realized Investments Gain Loss [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(21,383)		22,293		(48,576)		8,377
Nondesignated [Member] | Equity Contract [Member] | Net Investment Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0		0		0		0
Nondesignated [Member] | Equity Contract [Member] | Other Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0		0		0		0
Nondesignated [Member] | Equity Contract [Member] | Accumulated Other Comprehensive Income (loss) [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net	0	[1]	0	[1]	0	[1]	0	[1]
Nondesignated [Member] | Embedded Derivative [Member] | Net Realized Investments Gain Loss [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	(37,089)		(69,635)		(51,769)		(91,243)
Nondesignated [Member] | Embedded Derivative [Member] | Net Investment Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0		0		0		0
Nondesignated [Member] | Embedded Derivative [Member] | Other Income [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments Gain (Loss) Recognized In Income Net	0		0		0		0
Nondesignated [Member] | Embedded Derivative [Member] | Accumulated Other Comprehensive Income (loss) [Member]
Derivative Instruments Gain Loss [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net	$ 0	[1]	$ 0	[1]	$ 0	[1]	$ 0	[1]

[1] (1) Amounts deferred in accumulated other comprehensive income (loss)