Noninterest Expense (Details) - USD ($)	3 Months Ended							12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Noninterest Expense
Salaries and employee benefits								$ 50,927,000	$ 50,754,000	$ 43,762,000
Occupancy and equipment								8,018,000	6,647,000	5,411,000
Professional fees								5,338,000	3,259,000	1,969,000
Amortization of intangible assets								3,751,000	2,739,000	1,943,000
Software subscriptions								3,102,000	2,397,000	2,343,000
Data processing								2,770,000	2,890,000	1,978,000
Insurance expense								2,286,000	1,864,000	1,685,000
Supplemental retirement plan cost								1,724,000	1,240,000	202,000
Other								11,595,000	13,108,000	16,228,000
Total noninterest expense, excluding merger-related costs								89,511,000	84,898,000	75,521,000
Salaries and employee benefits merger-related costs								356,000	6,580,000	3,569,000
Other merger-related costs								2,245,000	4,500,000	5,598,000
Total merger-related costs	$ 101,000	$ 17,000	$ 59,000	$ 2,424,000	$ 9,879,000	$ 661,000	$ 540,000	$ 2,601,000	$ 11,080,000	$ 9,167,000