Derivative Financial Instruments (Derivative Asset and Liability Balance Sheet Offsetting) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Derivative Asset [Abstract]
Derivative Asset, Fair Value, Gross Asset	$ 49,213	$ 42,779
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	49,213	42,779
Derivative Asset, Fair Value, Gross Liability Not Offset in the Statement of Financial Condition	(14,441)	(753)
Derivative, Collateral, Obligation to Return Securities	(8,530)	0
Derivative assets	26,242	42,026
Derivative Liability [Abstract]
Derivative Liability, Fair Value, Gross Liability	37,665	42,458
Derivative Liability, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	37,665	42,458
Derivative Liability, Fair Value, Gross Asset Not Offset in the Statement of Financial Condition	(14,441)	(753)
Derivative, Collateral, Right to Reclaim Securities	(12,400)	(41,705)
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ 10,824	0
Security Owned and Pledged as Collateral, Fair Value		$ 45,500