Derivative Financial Instruments Fair Value Gains and Losses on Derivative Financial Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Income
Derivatives, Fair Value [Line Items]
Net fair value gains (losses) on derivative financial instruments	$ 1,157	$ 1,507	$ (2,037)
Interest rate locks with customers | Mortgage Banking Income
Derivatives, Fair Value [Line Items]
Gain (loss) on interest rate derivative instruments	(639)	(110)	577
Forward Commitments | Mortgage Banking Income
Derivatives, Fair Value [Line Items]
Gain (loss) on interest rate derivative instruments	1,930	1,345	(2,422)
Interest Rate Swaps with Customers | Other Income
Derivatives, Fair Value [Line Items]
Gain (loss) on interest rate derivative instruments	(25,461)	13,342	20,406
Interest Rate Swaps with Dealer Counterparties | Other Income
Derivatives, Fair Value [Line Items]
Gain (loss) on interest rate derivative instruments	25,461	(13,342)	(20,406)
Foreign Exchange Contracts with Correspondent Banks | Other Income
Derivatives, Fair Value [Line Items]
Gain (loss) on foreign currency derivatives	(487)	711	(880)
Foreign exchange contracts with customers | Other Income
Derivatives, Fair Value [Line Items]
Gain (loss) on foreign currency derivatives	$ 353	$ (439)	$ 688