Derivative Financial Instruments Fair Value Gains and Losses on Derivative Financial Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Income
Derivatives, Fair Value [Line Items]
Net fair value gains (losses) on derivative financial instruments	$ 1,507	$ (2,037)	$ (4,084)
Interest rate locks with customers | Mortgage Banking Income
Derivatives, Fair Value [Line Items]
Gain (loss) on interest rate derivative instruments	(110)	577	(5,949)
Forward Commitments | Mortgage Banking Income
Derivatives, Fair Value [Line Items]
Gain (loss) on interest rate derivative instruments	1,345	(2,422)	1,466
Interest Rate Swaps with Customers | Other Income
Derivatives, Fair Value [Line Items]
Gain (loss) on interest rate derivative instruments	13,342	20,406	(7,978)
Interest Rate Swaps with Dealer Counterparties | Other Income
Derivatives, Fair Value [Line Items]
Gain (loss) on interest rate derivative instruments	(13,342)	(20,406)	7,978
Foreign Exchange Contracts with Correspondent Banks | Other Income
Derivatives, Fair Value [Line Items]
Gain (loss) on foreign currency derivatives	711	(880)	507
Foreign exchange contracts with customers | Other Income
Derivatives, Fair Value [Line Items]
Gain (loss) on foreign currency derivatives	$ (439)	$ 688	$ (108)