ACL Activity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Allowance for credit losses
Balance at beginning of period	$ 150,190	$ 129,786	$ 124,490	$ 131,239
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)			3,720
Financing Receivable, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase			49
Financing Receivable, Credit Loss, Expense (Reversal)	13,552	0	36,296	57
Charge-offs	(2,668)	(2,859)	(5,235)	(6,200)
Recoveries	1,435	2,127	3,189	3,958
Balance at end of period	162,509	129,054	162,509	129,054
Residential Real Estate
Allowance for credit losses
Balance at beginning of period	9,315	10,711	10,111	10,631
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)			3,584
Financing Receivable, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase			0
Financing Receivable, Credit Loss, Expense (Reversal)	662	(105)	(3,707)	173
Charge-offs	(1)	(49)	(21)	(341)
Recoveries	10	138	19	232
Balance at end of period	9,986	10,695	9,986	10,695
Commercial Real Estate
Allowance for credit losses
Balance at beginning of period	70,848	72,328	69,496	72,448
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)			10,533
Financing Receivable, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase			49
Financing Receivable, Credit Loss, Expense (Reversal)	18,309	(196)	8,876	(344)
Charge-offs	(150)	(126)	(180)	(409)
Recoveries	97	441	330	752
Balance at end of period	89,104	72,447	89,104	72,447
Other Commercial
Allowance for credit losses
Balance at beginning of period	56,409	36,849	36,129	38,160
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)			(13,759)
Financing Receivable, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase			0
Financing Receivable, Credit Loss, Expense (Reversal)	(6,974)	(829)	27,159	(1,744)
Charge-offs	(1,088)	(358)	(1,873)	(1,198)
Recoveries	491	597	1,182	1,041
Balance at end of period	48,838	36,259	48,838	36,259
Home Equity
Allowance for credit losses
Balance at beginning of period	7,934	5,880	4,937	5,811
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)			3,400
Financing Receivable, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase			0
Financing Receivable, Credit Loss, Expense (Reversal)	2,174	(73)	1,666	(9)
Charge-offs	(193)	(20)	(194)	(28)
Recoveries	47	14	153	27
Balance at end of period	9,962	5,801	9,962	5,801
Other Consumer
Allowance for credit losses
Balance at beginning of period	5,684	4,018	3,817	4,189
Financing Receivable, Change in Method, Credit Loss Expense (Reversal)			(38)
Financing Receivable, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase			0
Financing Receivable, Credit Loss, Expense (Reversal)	(619)	1,203	2,302	1,981
Charge-offs	(1,236)	(2,306)	(2,967)	(4,224)
Recoveries	790	937	1,505	1,906
Balance at end of period	$ 4,619	$ 3,852	$ 4,619	$ 3,852