Allowance for Loan and Lease Losses - Activity (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) class segment	Jun. 30, 2018 USD ($)
Allowance for loan and lease losses
Number of primary portfolio segments | segment			3
Allowance for loan and lease losses:
Balance at beginning of period	$ 141,546	$ 138,574	$ 141,718	$ 137,253
Charge-offs	(9,505)	(6,324)	(18,127)	(13,424)
Recoveries	2,624	2,331	5,394	4,802
Increase (decrease) in Provision	3,870	6,020	9,550	11,970
Balance at end of period	138,535	140,601	$ 138,535	140,601
Commercial Lending
Allowance for loan and lease losses
Number of distinct portfolios | class			4
Commercial and Industrial
Allowance for loan and lease losses:
Balance at beginning of period	31,793	34,365	$ 34,501	34,006
Charge-offs	(2,000)		(2,000)	(475)
Recoveries	25	39	62	103
Increase (decrease) in Provision	1,870	835	(875)	1,605
Balance at end of period	31,688	35,239	31,688	35,239
Commercial Real Estate
Allowance for loan and lease losses:
Balance at beginning of period	21,197	19,254	19,725	18,044
Recoveries	32	32	63	154
Increase (decrease) in Provision	975	1,221	2,416	2,309
Balance at end of period	22,204	20,507	22,204	20,507
Construction
Allowance for loan and lease losses:
Balance at beginning of period	5,381	5,976	5,813	6,817
Increase (decrease) in Provision	(367)	1,630	(799)	789
Balance at end of period	5,014	7,606	5,014	7,606
Lease Financing
Allowance for loan and lease losses:
Balance at beginning of period	411	585	432	611
Charge-offs			(24)
Increase (decrease) in Provision	35	(28)	38	(54)
Balance at end of period	446	557	446	557
Residential mortgage
Allowance for loan and lease losses
Specific allocation for impaired loans in which the net collateral value exceeds the unpaid principal balance of the loan	0		0
Allowance for loan and lease losses:
Balance at beginning of period	44,911	43,220	44,906	42,852
Charge-offs		(34)		(34)
Recoveries	185	60	435	242
Increase (decrease) in Provision	(1,676)	679	(1,921)	865
Balance at end of period	43,420	43,925	43,420	43,925
Consumer
Allowance for loan and lease losses:
Balance at beginning of period	35,099	30,998	35,813	31,249
Charge-offs	(7,505)	(6,290)	(16,103)	(12,915)
Recoveries	2,382	2,200	4,834	4,303
Increase (decrease) in Provision	3,662	4,601	9,094	8,872
Balance at end of period	33,638	31,509	33,638	31,509
Unallocated
Allowance for loan and lease losses:
Balance at beginning of period	2,754	4,176	528	3,674
Increase (decrease) in Provision	(629)	(2,918)	1,597	(2,416)
Balance at end of period	$ 2,125	$ 1,258	$ 2,125	$ 1,258