Financial Derivatives Financial Derivatives (Schedule of Derivative Activity) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Interest Rate Swaps [Member]
Derivative [Line Items]
Average Monthly Notional Amount	$ 2,716,471	$ 2,227,315
Credit Default Swap [Member]
Derivative [Line Items]
Average Monthly Notional Amount	785,522	552,411
Total Return Swaps [Member]
Derivative [Line Items]
Average Monthly Notional Amount	201,734	55,108
Futures [Member]
Derivative [Line Items]
Average Monthly Notional Amount	1,046,384	738,830
Option contract [Member]
Derivative [Line Items]
Average Monthly Notional Amount	693,320	926,369
Forwards [Member]
Derivative [Line Items]
Average Monthly Notional Amount	77,054	42,143
Warrant [Member]
Derivative [Line Items]
Average Monthly Notional Amount	1,554	120
Loan Purchase Commitments [Member]
Derivative [Line Items]
Average Monthly Notional Amount	$ 240	$ 0