Securities - Schedule of Investments' Gross Unrealized Losses and Fair Value, aggregated by investment category and length of time (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Gain (Loss) on Investments [Line Items]
Less than 12 Months, Fair Value	$ 8,354	$ 0
Less than 12 Months, Unrealized Losses	(46)	0
12 Months or More, Fair Value	0	1,000
12 Months or More, Unrealized Losses	0	(1)
Total, Fair Value	8,354	1,000
Total, Unrealized Losses	(46)	(1)
Subordinated notes
Gain (Loss) on Investments [Line Items]
Less than 12 Months, Fair Value	8,354	0
Less than 12 Months, Unrealized Losses	(46)	0
12 Months or More, Fair Value	0	1,000
12 Months or More, Unrealized Losses	0	(1)
Total, Fair Value	8,354	1,000
Total, Unrealized Losses	(46)	(1)
State and municipal obligations
Gain (Loss) on Investments [Line Items]
Less than 12 Months, Fair Value	0	0
Less than 12 Months, Unrealized Losses	0	0
12 Months or More, Fair Value	0	0
12 Months or More, Unrealized Losses	0	0
Total, Fair Value	0	0
Total, Unrealized Losses	$ 0	$ 0