Noninterest Expense (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Noninterest Expense
Salaries and employee benefits									$ 50,754,000	$ 43,762,000	$ 35,719,000
Occupancy and equipment									6,647,000	5,411,000	4,578,000
Professional fees									3,259,000	1,969,000	2,982,000
Data processing									2,890,000	1,978,000	1,483,000
Amortization of intangible assets									2,739,000	1,943,000	1,361,000
Software subscriptions									2,397,000	2,343,000	1,831,000
Insurance expense									1,864,000	1,685,000	1,529,000
Other, excluding merger-related costs									14,348,000	16,430,000	11,255,000
Total noninterest expense, excluding merger-related costs									84,898,000	75,521,000	60,738,000
Salaries and employee benefits merger-related costs									6,580,000	3,569,000
Other merger-related costs									4,500,000	5,598,000	671,000
Pre-tax acquisition costs	$ 9,879,000	$ 661,000	$ 540,000		$ 139,000	$ 199,000	$ 8,214,000	$ 615,000	11,080,000	9,167,000	671,000
Total noninterest expense	$ 30,626,000	$ 17,909,000	$ 18,445,000	$ 17,918,000	$ 16,941,000	$ 17,728,000	$ 24,862,000	$ 15,990,000	$ 84,898,000	$ 75,521,000	$ 60,738,000