Derivative Financial Instruments Fair Value Gains and Losses on Derivative Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative [Line Items]
Net fair value gains on derivative financial instruments	$ 1,123	$ 929	$ 4,768	$ 769
Interest rate lock with customers [Member]
Derivative [Line Items]
Net fair value gains on derivative financial instruments	(59)	178	631	1,922
Forward Commitments [Member]
Derivative [Line Items]
Net fair value gains on derivative financial instruments	(48)	970	(2,270)	(1,042)
Interest Rate Swap with Customer [Member]
Derivative [Line Items]
Net fair value gains on derivative financial instruments	(47)	(1,948)	12,947	48,052
Interest Rate Swap with Counterparty [Member]
Derivative [Line Items]
Net fair value gains on derivative financial instruments	1,248	1,948	(6,582)	(48,052)
Foreign Exchange Contracts With Customer [Member]
Derivative [Line Items]
Net fair value gains on derivative financial instruments	140	47	(177)	502
Foreign Exchange Contracts With Correspondent Banks [Member]
Derivative [Line Items]
Net fair value gains on derivative financial instruments	$ (111)	$ (266)	$ 219	$ (613)