Acquisitions (Details) $ / shares in Units, $ in Thousands				9 Months Ended	12 Months Ended
	Aug. 21, 2020 USD ($) Branch	May 18, 2020 USD ($)	Nov. 08, 2019 USD ($) $ / shares shares	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Aug. 20, 2020	Nov. 12, 2019 Branch	Nov. 07, 2019
Business Acquisition [Line Items]
Goodwill				$ 11,953	$ 44,594
Commerce Financial Holdings, Inc.
Business Acquisition [Line Items]
Common stock surrendered		$ 100
Choice Bancorp Inc.
Business Acquisition [Line Items]
Common stock issued for consideration (in shares) | shares			1,184,102
Number of common stock for each outstanding share of common stock			0.00497
Value of common stock issued for consideration			$ 79,800
Price per share for stock issued in consideration (in dollars per share) | $ / shares			$ 67.39
Value of cash consideration			$ 1,700
Direct stock issuance costs for the merger charged against additional paid in capital			200
Amount of addition in assets			457,000
Amount of addition in loans			348,000
Amount of addition in deposits			289,000
Goodwill			45,000
Number of branches | Branch							2
Choice Bancorp Inc. | Core deposit intangibles
Business Acquisition [Line Items]
Intangible assets assumed			$ 1,700
Advantage Community Bancshares, Inc.
Business Acquisition [Line Items]
Amount of addition in assets	$ 172,000
Amount of addition in loans	88,000
Amount of addition in deposits	141,000
Goodwill	$ 12,000
Number of branches | Branch	4
Advantage Community Bancshares, Inc. | Core deposit intangibles
Business Acquisition [Line Items]
Intangible assets assumed	$ 1,000
Commerce Financial Holdings, Inc.
Business Acquisition [Line Items]
Termination costs		$ 500
Choice Bancorp Inc.
Business Acquisition [Line Items]
Percentage of assets represented by acquiree								0.12
Advantage Community Bancshares, Inc.
Business Acquisition [Line Items]
Percentage of assets represented by acquiree						0.04