Derivatives Volume of Activity (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Derivative [Line Items]
Beginning of Period Notional Amount	$ 9,680,000
Notional Amount of Derivative Instruments Added	3,500,000
Notional Amount of Derivative Instruments Terminated	9,300,000
End of Period Notional Amount	3,880,000
Forward Contracts [Member] | Pay-fixed interest rate swap
Derivative [Line Items]
End of Period Notional Amount	2,725,000	[1]
Interest Rate Swap | Receive-fixed interest rate swap
Derivative [Line Items]
Beginning of Period Notional Amount	425,000
Notional Amount of Derivative Instruments Added	0
Notional Amount of Derivative Instruments Terminated	0
End of Period Notional Amount	425,000
Interest Rate Swap | Pay-fixed interest rate swap
Derivative [Line Items]
Beginning of Period Notional Amount	2,955,000
Notional Amount of Derivative Instruments Added	3,500,000
Notional Amount of Derivative Instruments Terminated	3,000,000
End of Period Notional Amount	3,455,000	[1]
ERROR in label resolution.
Derivative [Line Items]
Beginning of Period Notional Amount	6,300,000
Notional Amount of Derivative Instruments Added	0
Notional Amount of Derivative Instruments Terminated	6,300,000
End of Period Notional Amount	$ 0

[1] The notional amount of pay-fixed interest rate swaps that were forward starting as of December 31, 2016 was $2,725,000.