Derivative Instruments (Derivative Instruments Offsetting Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Derivative Assets [Abstract]
Derivative Fair Value Of Free Standing Derivative Asset	$ 178,794		$ 101,352
Gross Amounts Offset in the Balance Sheet	(10,833)		(26,125)
Net Amounts Presented in the Balance Sheet	167,961		75,227
Derivative Asset, Fair Value of Collateral	(31,421)	[1]	(11,095)	[1]
Gross Amounts Not Offset in the Balance Sheet - Cash Collateral Pledged/Received	(117,525)	[2]	(51,006)	[2]
Net Amount	19,015		13,126
Derivative Liabilities [Abstract]
Gross Amounts Recognized	29,309		42,336
Gross Amounts Offset in the Balance Sheet	(10,833)		(26,125)
Net Amounts Presented in the Balance Sheet	18,476		16,211
Gross Amounts Not Offset in the Balance Sheet - Financial Instruments	(31,334)	[3]	(18,081)	[3]
Gross Amounts Not Offset in the Balance Sheet - Cash Collateral Pledged/Received	(941)	[4]	(8,033)	[4]
Net Amount	$ (13,799)		$ (9,903)

[1] Consists of U.S. Treasury securities.

[2] Included in cash and cash equivalents, with obligation to return cash collateral recorded in other liabilities.

[3] Included in other invested assets, primarily consists of U.S. Treasury securities.

[4] Consists of receivable from counterparty, included in other assets.