Fair Value - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Nonfinancial Assets and Liabilities [Abstract]
Outstanding balances in impaired loans	$ 45,600		$ 45,600		$ 48,900
Foreclosed assets re-measured after initial recognition			11,400	$ 16,200
Write-downs of allowance for foreclosed assets after initial recognition			965	2,200
Noninterest gain (loss) Mortgage banking, net for changes in fair value of LHFS	2,200	$ 58	1,700	3,700
Interest earned on LHFS included in Interest and fees on LHFS and LHFI	1,400	$ 1,200	2,300	$ 2,300
GNMA optional repurchase loans	$ 44,600		$ 44,600		$ 48,200
Maximum [Member]
Nonfinancial Assets and Liabilities [Abstract]
Estimated fair value of financial instruments with immediate and shorter-term maturities			90 days