Derivative Instruments (Narrative Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Derivative Instruments [Abstract]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ 1,000,000
Cumulative Foreign Currency Translation Gain Loss Recorded In Accumulated Other Comprehensive Income Loss For Net Investment In Foreign Operations Hedges	(16,400,000)	4,100,000
Gain Loss On Investments Related To Change In Fair Value Of Derivatives Excluding Embedded Derivatives	(61,400,000)	188,600,000	29,900,000
Embedded Derivative Gain Loss In Financial Statements From Use Of Own Credit Risk	(62,700,000)	23,100,000	(32,200,000)
Embedded Derivative Gain Loss On Variable Annuity Contracts In Financial Statements From Use Of Own Credit Risk	$ 16,500,000