Derivative Instruments (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	$ 2,100,000
Cumulative Foreign Currency Translation Gain Loss Recorded In Accumulated Other Comprehensive Income Loss For Net Investment In Foreign Operations Hedges	75,800,000	23,900,000
Gain Loss On Investments Related To Change In Fair Value Of Derivatives Excluding Embedded Derivatives	80,661,000	(177,258,000)	(61,446,000)
Embedded Derivative Gain Loss In Financial Statements From Use Of Own Credit Risk	1,600,000	1,600,000	62,700,000
Embedded Derivative Gain Loss On Variable Annuity Contracts In Financial Statements From Use Of Own Credit Risk	$ 1,600,000	$ (12,500,000)	$ 16,500,000