Acquisition - Narrative (Details) $ in Thousands		3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 01, 2019 USD ($) bank_branch shares	Sep. 30, 2019 USD ($) shares	Sep. 30, 2019 USD ($) shares	Dec. 31, 2019 USD ($)
Business Acquisition [Line Items]
Stock issued as part of acquisition, value		$ 229,926	$ 229,926
Common Stock
Business Acquisition [Line Items]
Issuance of common stock related to acquisition (in shares) | shares		6,383,806	6,383,806
Stock issued as part of acquisition, value		$ 798	$ 798
MBT
Business Acquisition [Line Items]
Percentage of interest acquired	100.00%
Number of banking centers acquired | bank_branch	20
Stock issued as part of acquisition, value	$ 229,900
Core deposit intangible	16,527
Operating revenue				$ 19,700
Non-recurring expenses				$ 19,700
MBT | Core deposit intangibles acquired
Business Acquisition [Line Items]
Core deposit intangible	$ 16,527
Acquired intangible asset, expected useful life	10 years
MBT | Common Stock
Business Acquisition [Line Items]
Number of shares of common stock	0.275
Issuance of common stock related to acquisition (in shares) | shares	6,400,000