Derivative Instruments - Gains (Losses) On Derivative Financial Instruments (Details) - Not designated as hedging instruments: - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Derivatives, Fair Value [Line Items]
Gains (losses) on derivative financial instruments	$ (212)	$ 1,408	$ 3,046	$ (929)
Interest rate contracts | Included in interest income on loans
Derivatives, Fair Value [Line Items]
Gains (losses) on derivative financial instruments	1,038	690	2,024	1,369
Interest rate lock commitments | Included in mortgage banking income
Derivatives, Fair Value [Line Items]
Gains (losses) on derivative financial instruments	(238)	(1,538)	1,946	1,315
Forward commitments | Included in mortgage banking income
Derivatives, Fair Value [Line Items]
Gains (losses) on derivative financial instruments	$ (1,012)	$ 2,256	$ (924)	$ (3,613)