Allowance for Credit Losses - Activity in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 155,105	$ 138,762	$ 151,859	$ 120,856
Loans charged-off	(2,987)	(1,983)	(14,137)	(5,904)
Charged-off loans recovered	978	1,752	3,812	6,285
Net (charge-offs) recoveries	(2,009)	(231)	(10,325)	381
Provision for loan losses	8,757	6,432	20,319	23,726
Ending balance	161,853	144,963	161,853	144,963
Commercial and Industrial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	94,384	74,257	90,956	57,232
Loans charged-off	(527)	(833)	(7,882)	(1,606)
Charged-off loans recovered	330	1,131	2,008	4,057
Net (charge-offs) recoveries	(197)	298	(5,874)	2,451
Provision for loan losses	6,815	9,442	15,920	24,314
Ending balance	101,002	83,997	101,002	83,997
Commercial Real Estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	48,978	53,812	49,650	54,954
Loans charged-off	(158)	0	(158)	(348)
Charged-off loans recovered	28	12	71	396
Net (charge-offs) recoveries	(130)	12	(87)	48
Provision for loan losses	(77)	(3,694)	(792)	(4,872)
Ending balance	48,771	50,130	48,771	50,130
Residential Mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	5,219	4,624	5,041	3,605
Loans charged-off	(111)	0	(126)	(167)
Charged-off loans recovered	3	9	13	269
Net (charge-offs) recoveries	(108)	9	(113)	102
Provision for loan losses	191	286	374	1,212
Ending balance	5,302	4,919	5,302	4,919
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	6,524	6,069	6,212	5,065
Loans charged-off	(2,191)	(1,150)	(5,971)	(3,783)
Charged-off loans recovered	617	600	1,720	1,563
Net (charge-offs) recoveries	(1,574)	(550)	(4,251)	(2,220)
Provision for loan losses	1,828	398	4,817	3,072
Ending balance	$ 6,778	$ 5,917	$ 6,778	$ 5,917