Derivative Financial Instruments Fair Value Gains and Losses on Derivative Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative [Line Items]
Net fair value gains (losses) on derivative financial instruments	$ 3,022	$ (381)	$ 3,645	$ (160)
Interest rate lock with customers [Member]
Derivative [Line Items]
Net fair value gains (losses) on derivative financial instruments	(155)	512	690	1,744
Forward Commitments [Member]
Derivative [Line Items]
Net fair value gains (losses) on derivative financial instruments	157	(906)	(2,222)	(2,012)
Interest Rate Swap with Customer [Member]
Derivative [Line Items]
Net fair value gains (losses) on derivative financial instruments	13,809	20,569	12,994	50,000
Interest Rate Swap with Counterparty [Member]
Derivative [Line Items]
Net fair value gains (losses) on derivative financial instruments	(10,831)	(20,569)	(7,830)	(50,000)
Foreign Exchange Contracts With Customer [Member]
Derivative [Line Items]
Net fair value gains (losses) on derivative financial instruments	(325)	81	(317)	455
Foreign Exchange Contracts With Correspondent Banks [Member]
Derivative [Line Items]
Net fair value gains (losses) on derivative financial instruments	$ 367	$ (68)	$ 330	$ (347)