Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax expense at federal statutory rate									$ 10,021	$ 8,313	$ 11,613
State franchise tax expense, net of federal tax effect									3,872	3,390	2,363
Tax exempt municipal income									(952)	(852)	(1,299)
Affordable housing tax credits									(538)	(632)	(711)
Effect of the tax act									0	0	2,710
Excess tax benefit of stock-based compensation									(133)	(177)	(248)
Other									(513)	(135)	(788)
Income Tax Expense (Benefit), Total	$ 2,902	$ 2,854	$ 3,169	$ 2,832	$ 2,997	$ 2,171	$ 2,643	$ 2,096	$ 11,757	$ 9,907	$ 13,640
Effective tax rate									24.60%	25.00%	41.10%