Derivative Instruments and Hedging Activities Schedule of Credit Default Swaps, Receive Protection (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Derivative [Line Items]
Derivative, Notional Amount	$ (22,062,904)	$ (21,998,381)	$ (26,141,370)	$ (28,317,580)	$ (27,401,335)	$ (48,115,523)
Credit Default Swap, Buying Protection [Member]
Derivative [Line Items]
Derivative, Average Implied Credit Spread	496.00	183.60
Derivative, Notional Amount	$ (25,000)	$ (125,000)
Derivative, Fair Value, Net	(52)	(703)
Derivative, Cost	(4,062)	(4,322)
Derivative, Unrealized Gains (Losses)	$ (4,114)	$ (5,025)
Maturity Date, 06/20/2016 [Member] | Credit Default Swap, Buying Protection [Member]
Derivative [Line Items]
Derivative, Maturity Date		Jun. 20, 2016
Derivative, Average Implied Credit Spread		105.50
Derivative, Notional Amount		$ (100,000)
Derivative, Fair Value, Net		(502)
Derivative, Cost		(260)
Derivative, Unrealized Gains (Losses)		$ (762)
Maturity Date, 12/20/2016 [Member] | Credit Default Swap, Buying Protection [Member]
Derivative [Line Items]
Derivative, Maturity Date	Dec. 20, 2016	Dec. 20, 2016
Derivative, Average Implied Credit Spread	496.00	496.00
Derivative, Notional Amount	$ (25,000)	$ (25,000)
Derivative, Fair Value, Net	(52)	(201)
Derivative, Cost	(4,062)	(4,062)
Derivative, Unrealized Gains (Losses)	(4,114)	(4,263)
Derivative Financial Instruments, Liabilities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(9,221,580)	(1,362,384)
Derivative, Fair Value, Net	$ 39,918	$ 7,285