Fair Value - Additional Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) Region	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Region	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Nonfinancial Assets and Liabilities [Abstract]
Outstanding balances in impaired loans	$ 49,500		$ 49,500		$ 27,100
Key market regions | Region	5		5
Foreclosed assets re-measured after initial recognition			$ 22,000	$ 26,500
Write-downs of allowance for foreclosed assets after initial recognition			2,600	3,700
Noninterest gain (loss) Mortgage banking, net for changes in fair value of LHFS	$ (202)	$ (1,100)	3,500	2,600
Interest earned on LHFS included in Interest and fees on LHFS and LHFI	1,400	$ 1,500	3,700	$ 3,700
GNMA optional repurchase loans	$ 48,100		$ 48,100		$ 43,900
Maximum [Member]
Nonfinancial Assets and Liabilities [Abstract]
Estimated fair value of financial instruments with immediate and shorter-term maturities			90 days