Derivative Instruments - Gains (Losses) On Derivative Financial Instruments (Details) - Not designated as hedging instruments: - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivatives, Fair Value [Line Items]
Gains (losses) on derivative financial instruments	$ 2,144	$ 725	$ 5,190	$ (204)
Interest rate contracts | Included in interest income on loans
Derivatives, Fair Value [Line Items]
Gains (losses) on derivative financial instruments	1,042	1,652	3,066	3,021
Interest rate lock commitments | Included in mortgage banking income
Derivatives, Fair Value [Line Items]
Gains (losses) on derivative financial instruments	(1,737)	(441)	209	874
Forward commitments | Included in mortgage banking income
Derivatives, Fair Value [Line Items]
Gains (losses) on derivative financial instruments	$ 2,839	$ (486)	$ 1,915	$ (4,099)