Goodwill and Other Intangible Assets - Current Year Amortization Expense for Finite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Finite-Lived Intangible Assets [Line Items]
Total intangible amortization	$ 1,996	$ 1,765	$ 6,159	$ 5,010
Core deposit intangibles
Finite-Lived Intangible Assets [Line Items]
Total intangible amortization	1,963	1,732	6,060	4,911
Customer relationship intangible
Finite-Lived Intangible Assets [Line Items]
Total intangible amortization	$ 33	$ 33	$ 99	$ 99