Revenue from Contracts with Customers (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 17,126,000	$ 14,570,000	$ 46,889,000	$ 41,219,000
Other sources of noninterest income	32,454,000	36,904,000	115,377,000	105,145,000
Total noninterest income	49,580,000	51,474,000	162,266,000	146,364,000
Contract assets	0		0		$ 0
Contract liabilities	0		0		$ 0
Consumer and Business Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	12,396,000	10,785,000	33,347,000	30,155,000
Other sources of noninterest income	5,030,000	4,318,000	14,424,000	13,223,000
Total noninterest income	17,426,000	15,103,000	47,771,000	43,378,000
Commercial Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,723,000	3,776,000	13,488,000	11,029,000
Other sources of noninterest income	24,261,000	29,955,000	81,839,000	80,902,000
Total noninterest income	28,984,000	33,731,000	95,327,000	91,931,000
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	7,000	9,000	54,000	35,000
Other sources of noninterest income	3,163,000	2,631,000	19,114,000	11,020,000
Total noninterest income	3,170,000	2,640,000	19,168,000	11,055,000
Deposit service charges and related fee income
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	11,541,000	8,788,000	31,001,000	26,017,000
Deposit service charges and related fee income | Consumer and Business Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6,995,000	5,345,000	18,705,000	15,975,000
Deposit service charges and related fee income | Commercial Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,539,000	3,434,000	12,242,000	10,007,000
Deposit service charges and related fee income | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	7,000	9,000	54,000	35,000
Card income
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,032,000	941,000	2,891,000	2,787,000
Card income | Consumer and Business Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	848,000	796,000	2,385,000	2,303,000
Card income | Commercial Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	184,000	145,000	506,000	484,000
Card income | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0	0	0
Wealth management fees
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,553,000	4,841,000	12,997,000	12,415,000
Wealth management fees | Consumer and Business Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,553,000	4,644,000	12,257,000	11,877,000
Wealth management fees | Commercial Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	197,000	740,000	538,000
Wealth management fees | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 0	$ 0	$ 0	$ 0