Derivative Financial Instruments Fair Value Gains and Losses on Derivative Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative [Line Items]
Net fair value gains (losses) on derivative financial instruments	$ 221	$ 1,919
Interest rate lock with customers [Member]
Derivative [Line Items]
Net fair value gains (losses) on derivative financial instruments	1,232	1,122
Forward Commitments [Member]
Derivative [Line Items]
Net fair value gains (losses) on derivative financial instruments	(1,106)	554
Interest Rate Swap with Customer [Member]
Derivative [Line Items]
Net fair value gains (losses) on derivative financial instruments	29,431	9,404
Interest Rate Swap with Counterparty [Member]
Derivative [Line Items]
Net fair value gains (losses) on derivative financial instruments	(29,431)	(9,404)
Foreign Exchange Contracts With Customer [Member]
Derivative [Line Items]
Net fair value gains (losses) on derivative financial instruments	374	567
Foreign Exchange Contracts With Correspondent Banks [Member]
Derivative [Line Items]
Net fair value gains (losses) on derivative financial instruments	$ (279)	$ (324)