Derivative Financial Instruments (Schedule of offsetting financial assets and liabilities for non-customer derivative positions) (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Derivative Asset, Gross Amount		$ 35,727	$ 4,945
Derivative Asset, Total, Amount Offset		(35,727)	(4,945)
Derivative Asset, Net Amount	[1],[2]	0	0
Derivative Liability, Gross Amount		25,300	41,727
Derivative Liability, Total, Amount Offset		(24,854)	(36,275)
Derivative Liability, Net Amount	[1],[2]	446	5,452
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Gross Amount		3,270	2,507
Derivative Asset, Total, Amount Offset		(3,270)	(2,507)
Derivative Asset, Net Amount	[1],[2]	0	0
Derivative Liability, Gross Amount		792	1,359
Derivative Liability, Total, Amount Offset		(792)	(1,359)
Derivative Liability, Net Amount	[1],[2]	0	0
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Gross Amount		32,457	2,438
Derivative Asset, Total, Amount Offset		(32,457)	(2,438)
Derivative Asset, Net Amount	[1],[2]	0	0
Derivative Liability, Gross Amount		24,508	40,368
Derivative Liability, Total, Amount Offset		(24,062)	(34,916)
Derivative Liability, Net Amount	[1],[2]	$ 446	$ 5,452

[1] Net amount excludes $42.5 million and $20.2 million of initial margin requirements posted at the derivative clearing organization at December 31, 2016 and December 31, 2015, respectively. Initial margin is recorded as a component of accrued interest receivable and other assets in the accompanying Consolidated Balance Sheets

[2] Net amount is net of $10.9 million and $31.3 million of cash collateral at December 31, 2016 and December 31, 2015, respectively, as presented in the accompanying Consolidated Balance Sheets.