Derivative Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Interest Rate Lock Commitments
Derivative Financial Instruments
Aggregate notional amount	$ 50,400		$ 50,400		$ 51,700
Forward Sales Commitments
Derivative Financial Instruments
Aggregate notional amount	82,300		82,300		139,700
Interest rate lock commitments and forward sales commitments
Gross gains and losses on derivative assets and liabilities recorded in Consolidated Statements of Income
Net gains (losses)	80	$ 739	(273)	$ 1,527
Interest rate lock commitments and forward sales commitments | Non-interest income
Gross gains and losses on derivative assets and liabilities recorded in Consolidated Statements of Income
Gross gains	641	3,822	2,396	12,629
Interest rate lock commitments and forward sales commitments | Non-interest expense
Gross gains and losses on derivative assets and liabilities recorded in Consolidated Statements of Income
Gross (losses)	(561)	(3,083)	(2,669)	(11,102)
Interest rate lock commitments and forward sales commitments | Other assets
Fair values of derivative assets and liabilities recorded in consolidated balance sheets
Fair value recorded in other assets	322		322		675
Interest rate lock commitments and forward sales commitments | Other liabilities
Fair values of derivative assets and liabilities recorded in consolidated balance sheets
Fair value recorded in other liabilities	561		561		2,148
Interest rate swap
Derivative Financial Instruments
Aggregate notional amount	188,800		188,800		161,300
Variable rate, commercial loans that are supported by the interest rate swap contracts	94,400		94,400		80,700
Derivative cash pledged					2,000
Derivative securities pledged	300		300		400
Interest rate swap | Non-interest income
Gross gains and losses on derivative assets and liabilities recorded in Consolidated Statements of Income
Gross gains	724	128	2,167	429
Interest rate swap | Non-interest expense
Gross gains and losses on derivative assets and liabilities recorded in Consolidated Statements of Income
Gross (losses)	(724)	$ (128)	(2,167)	$ (429)
Interest rate swap | Other assets
Fair values of derivative assets and liabilities recorded in consolidated balance sheets
Fair value recorded in other assets	2,428		2,428		262
Interest rate swap | Other liabilities
Fair values of derivative assets and liabilities recorded in consolidated balance sheets
Fair value recorded in other liabilities	$ 2,428		$ 2,428		$ 262