Revenue from Contracts with Customers (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 13,312,000	$ 13,854,000	$ 41,336,000	$ 41,815,000
Other sources of noninterest income	33,190,000	35,616,000	127,878,000	170,727,000
Total noninterest income	46,502,000	49,470,000	169,214,000	212,542,000
Contract with customer, asset, net	0		0		$ 0
Contracts with customers, receivables, net	0		0		$ 0
Retail Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	9,838,000	10,243,000	30,890,000	30,788,000
Other sources of noninterest income	3,299,000	5,825,000	41,280,000	12,485,000
Total noninterest income	13,137,000	16,068,000	72,170,000	43,273,000
Commercial Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,468,000	3,479,000	10,034,000	10,669,000
Other sources of noninterest income	24,393,000	26,837,000	76,009,000	71,965,000
Total noninterest income	27,861,000	30,316,000	86,043,000	82,634,000
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6,000	132,000	412,000	358,000
Other sources of noninterest income	5,498,000	2,954,000	10,589,000	86,277,000
Total noninterest income	5,504,000	3,086,000	11,001,000	86,635,000
Deposit service charges and related fee income
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	8,627,000	9,187,000	26,799,000	26,961,000
Deposit service charges and related fee income | Retail Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5,488,000	6,082,000	17,240,000	18,076,000
Deposit service charges and related fee income | Commercial Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,133,000	2,973,000	9,147,000	8,527,000
Deposit service charges and related fee income | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	6,000	132,000	412,000	358,000
Card income
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,150,000	1,206,000	3,548,000	3,677,000
Card income | Retail Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	949,000	996,000	2,952,000	3,052,000
Card income | Commercial Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	201,000	210,000	596,000	625,000
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	3,535,000	3,461,000	10,989,000	11,177,000
Wealth management fees | Retail Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,401,000	3,165,000	10,698,000	9,660,000
Wealth management fees | Commercial Banking
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	134,000	296,000	291,000	1,517,000
Wealth management fees | Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 0	$ 0	$ 0	$ 0