Basis of Presentation and Summary of Significant Accounting Policies (Details) $ / shares in Units, $ in Thousands			9 Months Ended
	Aug. 10, 2020 USD ($) $ / shares shares	Jan. 02, 2020 USD ($)	Sep. 30, 2020 USD ($) center office $ / shares	Sep. 30, 2019 USD ($)
Business Acquisition [Line Items]
Number of offices | office			17
Number of mortgage loan production office | center			1
Preferred stock, liquidation preference (in dollars per share) | $ / shares			$ 2,500
Net proceeds from issuance of preferred stock | $			$ 23,370	$ 0
Series B Preferred Stock
Business Acquisition [Line Items]
Preferred stock, interest rate	7.50%
Depositary Shares
Business Acquisition [Line Items]
Sale of stock, number of shares issued (in shares) | shares	1,000,000
Percentage of interest in a share of perpetual preferred stock	1.00%
Preferred stock, liquidation preference (in dollars per share) | $ / shares	$ 25
Sale of stock, consideration received on transaction | $	$ 25,000
Sale of stock, underwriting discounts and offering expenses | $	1,600
Net proceeds from issuance of preferred stock | $	$ 23,400
Metro Detroit
Business Acquisition [Line Items]
Number of banking centers | center			11
Grand Rapids
Business Acquisition [Line Items]
Number of banking centers | center			1
Jackson
Business Acquisition [Line Items]
Number of banking centers | center			1
Ann Arbor
Business Acquisition [Line Items]
Number of banking centers | center			3
Ann Arbor Bancorp, Inc
Business Acquisition [Line Items]
Consideration from business acquisition | $		$ 67,900