ALLL Activity (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for loan and lease losses
Balance at beginning of period				$ 129,697				$ 129,753	$ 129,697	$ 129,753	$ 130,351
Provision for loan losses	$ 1,139	$ 626	$ 0	568	$ 411	$ 826	$ 282	765	2,333	2,284	1,912
Charge-offs									(11,496)	(7,002)	(7,603)
Recoveries									9,038	4,662	5,093
Balance at end of period	129,572				129,697				129,572	129,697	129,753
Residential Real Estate | Residential Real Estate
Allowance for loan and lease losses
Balance at beginning of period				14,427				14,680	14,427	14,680	14,067
Provision for loan losses									(1,734)	640	716
Charge-offs									(464)	(985)	(431)
Recoveries									207	92	328
Balance at end of period	12,436				14,427				12,436	14,427	14,680
Commercial | Commercial Real Estate
Allowance for loan and lease losses
Balance at beginning of period				67,877				67,799	67,877	67,799	70,332
Provision for loan losses									(2,686)	(696)	(2,877)
Charge-offs									(3,082)	(1,920)	(1,802)
Recoveries									3,664	2,694	2,146
Balance at end of period	65,773				67,877				65,773	67,877	67,799
Commercial | Other Commercial
Allowance for loan and lease losses
Balance at beginning of period				32,525				30,891	32,525	30,891	28,630
Provision for loan losses									4,835	3,030	3,708
Charge-offs									(1,144)	(2,322)	(3,058)
Recoveries									1,607	926	1,611
Balance at end of period	37,823				32,525				37,823	32,525	30,891
Consumer and Other | Home Equity
Allowance for loan and lease losses
Balance at beginning of period				8,998				9,963	8,998	9,963	9,299
Provision for loan losses									(520)	(480)	1,254
Charge-offs									(1,185)	(809)	(1,038)
Recoveries									279	324	448
Balance at end of period	7,572				8,998				7,572	8,998	9,963
Consumer and Other | Other Consumer
Allowance for loan and lease losses
Balance at beginning of period				$ 5,870				$ 6,420	5,870	6,420	8,023
Provision for loan losses									2,438	(210)	(889)
Charge-offs									(5,621)	(966)	(1,274)
Recoveries									3,281	626	560
Balance at end of period	$ 5,968				$ 5,870				$ 5,968	$ 5,870	$ 6,420