Revenue from Contracts with Customers (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									$ 53,644,000	$ 54,899,000	$ 52,254,000
Other sources of noninterest income									157,265,000	202,849,000	130,024,000
Total noninterest income	$ 41,695,000	$ 46,502,000	$ 48,268,000	$ 74,444,000	$ 45,206,000	$ 49,470,000	$ 47,244,000	$ 115,828,000	210,909,000	257,748,000	182,278,000
Contract with customer, asset, net	0				0				0	0
Contracts with customers, receivables, net	$ 0				$ 0				0	0
Deposit service charges and related fee income
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									35,223,000	36,049,000	34,510,000
Card income
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									4,636,000	4,876,000	5,144,000
Wealth management fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									13,785,000	13,974,000	12,600,000
Consumer and Business Banking
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									39,711,000	40,265,000	37,742,000
Other sources of noninterest income									45,896,000	14,186,000	13,509,000
Total noninterest income									85,607,000	54,451,000	51,251,000
Consumer and Business Banking | Deposit service charges and related fee income
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									22,474,000	24,109,000	23,965,000
Consumer and Business Banking | Card income
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									3,880,000	3,938,000	4,352,000
Consumer and Business Banking | Wealth management fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									13,357,000	12,218,000	9,425,000
Commercial Banking
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									13,510,000	14,170,000	14,134,000
Other sources of noninterest income									96,777,000	95,919,000	81,422,000
Total noninterest income									110,287,000	110,089,000	95,556,000
Commercial Banking | Deposit service charges and related fee income
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									12,326,000	11,476,000	10,200,000
Commercial Banking | Card income
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									756,000	938,000	763,000
Commercial Banking | Wealth management fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									428,000	1,756,000	3,171,000
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									423,000	464,000	378,000
Other sources of noninterest income									14,592,000	92,744,000	35,093,000
Total noninterest income									15,015,000	93,208,000	35,471,000
Other | Deposit service charges and related fee income
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									423,000	464,000	345,000
Other | Card income
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									0	0	29,000
Other | Wealth management fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer									$ 0	$ 0	$ 4,000