Derivative Instruments (Gross Notional Amount and Fair Value of Derivatives Contracts) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Notional Value
Total Derivatives	$ 11,919,480	[1]	$ 10,959,486	[1]
Fair Value Asset
Total Derivatives	103,058	[1]	174,087	[1]
Fair Value Liability
Total Derivatives	91,385	[1]	42,352	[1]
Designated as Hedging Instrument [Member]
Notional Value
Qualifying Hedge Relationships	72,247		65,612
Fair Value Asset
Derivative Fair Value Of Derivative Asset	361		192
Fair Value Liability
Derivative Fair Value Of Derivative Liability	3,886		3,309
Nondesignated [Member]
Notional Value
Qualifying Hedge Relationships	11,847,233		10,893,874
Fair Value Asset
Derivative Fair Value Of Derivative Asset	102,697		173,895
Fair Value Liability
Derivative Fair Value Of Derivative Liability	87,499		39,043
Interest Rate Contract [Member] | Interest Rate Swap Member | Nondesignated [Member]
Notional Value
Qualifying Hedge Relationships	2,332,950		2,332,950
Fair Value Asset
Derivative Fair Value Of Derivative Asset	78,215		139,258
Fair Value Liability
Derivative Fair Value Of Derivative Liability	77,657		24,075
Interest Rate Contract [Member] | InterestRateOption [Member] | Nondesignated [Member]
Notional Value
Qualifying Hedge Relationships	100,000		100,000
Fair Value Asset
Derivative Fair Value Of Derivative Asset	8,476		15,330
Fair Value Liability
Derivative Fair Value Of Derivative Liability	0		0
Credit Risk Contract [Member] | Credit Default Swap Member | Nondesignated [Member]
Notional Value
Qualifying Hedge Relationships	6,050		345,050
Fair Value Asset
Derivative Fair Value Of Derivative Asset	0		411
Fair Value Liability
Derivative Fair Value Of Derivative Liability	125		1,413
Cross Currency Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Notional Value
Qualifying Hedge Relationships	72,247		65,612
Fair Value Asset
Derivative Fair Value Of Derivative Asset	361		192
Fair Value Liability
Derivative Fair Value Of Derivative Liability	3,886		3,309
Cross Currency Interest Rate Contract [Member] | Currency Swap Member | Nondesignated [Member]
Notional Value
Qualifying Hedge Relationships	55,919		61,126
Fair Value Asset
Derivative Fair Value Of Derivative Asset	451		1,715
Fair Value Liability
Derivative Fair Value Of Derivative Liability	1,912		2,894
Equity Contract [Member] | Equity Options [Member] | Nondesignated [Member]
Notional Value
Qualifying Hedge Relationships	9,145,307		7,800,982
Fair Value Asset
Derivative Fair Value Of Derivative Asset	11,662		16,988
Fair Value Liability
Derivative Fair Value Of Derivative Liability	6,486		6,920
Equity Contract [Member] | Total Return Swap Member | Nondesignated [Member]
Notional Value
Qualifying Hedge Relationships	207,007		253,766
Fair Value Asset
Derivative Fair Value Of Derivative Asset	3,893		193
Fair Value Liability
Derivative Fair Value Of Derivative Liability	$ 1,319		$ 3,741

[1] (1) Excludes embedded derivatives which contain multiple underlyings. The fair value of these embedded derivatives was a liability of $1,304 million and $1,793 million as of September 30, 2013 and December 31, 2012, respectively, included in “Future policy benefits.”