Allowance for Credit Losses - Amortized Cost Basis by Year of Origination and Credit Quality Indicator (Details) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Credit quality
Total loans and leases	$ 12,891,743,000	$ 12,961,999,000
Loss
Credit quality
Total loans and leases	0	0
Residential mortgage
Credit quality
2021/2022	242,485,000	1,304,978,000
2020/2021	1,287,330,000	753,668,000
2019/2020	725,918,000	363,415,000
2018/2019	339,678,000	266,368,000
2017/2018	243,470,000	332,041,000
Prior	1,313,531,000	1,062,135,000
Revolving Loans Amortized Cost Basis	43,000	44,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	1,369,000	718,000
Total loans and leases	4,153,824,000	4,083,367,000
Residential mortgage | 740 and greater
Credit quality
2021/2022	185,434,000	1,101,958,000
2020/2021	1,096,789,000	635,061,000
2019/2020	615,500,000	286,993,000
2018/2019	264,419,000	198,622,000
2017/2018	183,368,000	251,906,000
Prior	1,012,447,000	829,175,000
Total loans and leases	3,357,957,000	3,303,715,000
Residential mortgage | 680 - 739
Credit quality
2021/2022	26,812,000	140,997,000
2020/2021	128,172,000	81,590,000
2019/2020	72,766,000	45,163,000
2018/2019	44,872,000	27,315,000
2017/2018	25,913,000	32,855,000
Prior	159,950,000	125,906,000
Total loans and leases	458,485,000	453,826,000
Residential mortgage | 620 - 679
Credit quality
2021/2022	3,088,000	15,781,000
2020/2021	13,196,000	11,943,000
2019/2020	12,304,000	5,268,000
2018/2019	5,995,000	10,149,000
2017/2018	5,021,000	9,069,000
Prior	39,145,000	37,404,000
Total loans and leases	78,749,000	89,614,000
Residential mortgage | 550 - 619
Credit quality
2021/2022		1,735,000
2020/2021	2,267,000	873,000
2019/2020	1,570,000	698,000
2018/2019	720,000	533,000
2017/2018	731,000	2,033,000
Prior	8,847,000	7,475,000
Total loans and leases	14,135,000	13,347,000
Residential mortgage | Less than 550
Credit quality
2021/2022	2,116,000
2020/2021	228,000
2019/2020	60,000
2018/2019		345,000
2017/2018	82,000	2,603,000
Prior	4,098,000	2,838,000
Total loans and leases	6,584,000	5,786,000
Residential mortgage | No Score
Credit quality
2021/2022	6,550,000	18,882,000
2020/2021	15,806,000	7,938,000
2019/2020	7,676,000	15,051,000
2018/2019	13,968,000	18,107,000
2017/2018	17,545,000	17,333,000
Prior	56,444,000	42,185,000
Total loans and leases	117,989,000	119,496,000
Residential mortgage | Fico Other
Credit quality
2021/2022	18,485,000	25,625,000
2020/2021	30,872,000	16,263,000
2019/2020	16,042,000	10,242,000
2018/2019	9,704,000	11,297,000
2017/2018	10,810,000	16,242,000
Prior	32,600,000	17,152,000
Revolving Loans Amortized Cost Basis	43,000	44,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	1,369,000	718,000
Total loans and leases	119,925,000	97,583,000
Home equity line
Credit quality
Revolving Loans Amortized Cost Basis	908,958,000	867,251,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	9,143,000	9,357,000
Total loans and leases	918,101,000	876,608,000
Home equity line | 740 and greater
Credit quality
Revolving Loans Amortized Cost Basis	705,570,000	671,566,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	1,892,000	1,873,000
Total loans and leases	707,462,000	673,439,000
Home equity line | 680 - 739
Credit quality
Revolving Loans Amortized Cost Basis	147,290,000	141,889,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	3,202,000	3,968,000
Total loans and leases	150,492,000	145,857,000
Home equity line | 620 - 679
Credit quality
Revolving Loans Amortized Cost Basis	39,370,000	37,815,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	2,129,000	2,500,000
Total loans and leases	41,499,000	40,315,000
Home equity line | 550 - 619
Credit quality
Revolving Loans Amortized Cost Basis	10,310,000	9,090,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	1,426,000	948,000
Total loans and leases	11,736,000	10,038,000
Home equity line | Less than 550
Credit quality
Revolving Loans Amortized Cost Basis	1,482,000	2,574,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	494,000	68,000
Total loans and leases	1,976,000	2,642,000
Home equity line | No Score
Credit quality
Revolving Loans Amortized Cost Basis	4,936,000	4,317,000
Total loans and leases	4,936,000	4,317,000
Total loans
Credit quality
2021/2022	761,482,000	3,157,488,000
2020/2021	2,980,748,000	1,588,735,000
2019/2020	1,527,891,000	1,632,764,000
2018/2019	1,456,656,000	1,164,714,000
2017/2018	1,044,535,000	954,259,000
Prior	3,069,935,000	2,359,432,000
Revolving Loans Amortized Cost Basis	1,989,340,000	2,033,383,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	61,156,000	71,224,000
Total loans and leases	12,891,743,000	12,961,999,000
Residential. Mortgage
Credit quality
Total loans and leases	4,153,824,000	4,083,367,000
Home equity Line
Credit quality
Total loans and leases	918,101,000	876,608,000
Consumer
Credit quality
2021/2022	94,489,000	306,140,000
2020/2021	286,366,000	174,166,000
2019/2020	156,220,000	184,913,000
2018/2019	161,649,000	124,197,000
2017/2018	103,564,000	67,459,000
Prior	70,881,000	24,158,000
Revolving Loans Amortized Cost Basis	327,826,000	344,870,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	3,839,000	4,036,000
Total loans and leases	1,204,834,000	1,229,939,000
Consumer | 740 and greater
Credit quality
2021/2022	60,821,000	155,929,000
2020/2021	145,550,000	83,337,000
2019/2020	74,436,000	79,617,000
2018/2019	68,970,000	56,707,000
2017/2018	46,731,000	24,525,000
Prior	24,261,000	8,067,000
Revolving Loans Amortized Cost Basis	112,298,000	117,843,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	217,000	209,000
Total loans and leases	533,284,000	526,234,000
Consumer | 680 - 739
Credit quality
2021/2022	26,319,000	93,214,000
2020/2021	87,933,000	56,327,000
2019/2020	50,976,000	55,126,000
2018/2019	48,120,000	34,049,000
2017/2018	28,498,000	17,527,000
Prior	18,340,000	6,315,000
Revolving Loans Amortized Cost Basis	68,407,000	69,366,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	647,000	707,000
Total loans and leases	329,240,000	332,631,000
Consumer | 620 - 679
Credit quality
2021/2022	6,222,000	41,671,000
2020/2021	39,016,000	21,986,000
2019/2020	19,677,000	28,491,000
2018/2019	25,307,000	19,403,000
2017/2018	16,453,000	12,952,000
Prior	14,473,000	5,324,000
Revolving Loans Amortized Cost Basis	30,462,000	31,165,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	1,038,000	1,175,000
Total loans and leases	152,648,000	162,167,000
Consumer | 550 - 619
Credit quality
2021/2022	292,000	7,836,000
2020/2021	7,159,000	8,265,000
2019/2020	7,314,000	13,265,000
2018/2019	11,776,000	10,497,000
2017/2018	8,904,000	7,469,000
Prior	8,485,000	3,244,000
Revolving Loans Amortized Cost Basis	10,352,000	10,359,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	1,129,000	1,089,000
Total loans and leases	55,411,000	62,024,000
Consumer | Less than 550
Credit quality
2021/2022	53,000	2,272,000
2020/2021	2,003,000	3,867,000
2019/2020	3,445,000	6,646,000
2018/2019	5,732,000	3,484,000
2017/2018	2,939,000	2,739,000
Prior	3,089,000	1,175,000
Revolving Loans Amortized Cost Basis	3,166,000	3,195,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	471,000	536,000
Total loans and leases	20,898,000	23,914,000
Consumer | No Score
Credit quality
2021/2022	280,000	481,000
2020/2021	458,000	19,000
2019/2020	9,000	56,000
2018/2019	53,000	40,000
2017/2018	35,000	65,000
Prior	52,000	2,000
Revolving Loans Amortized Cost Basis	35,063,000	35,414,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	337,000	320,000
Total loans and leases	36,287,000	36,397,000
Consumer | Fico Other
Credit quality
2021/2022	502,000	4,737,000
2020/2021	4,247,000	365,000
2019/2020	363,000	1,712,000
2018/2019	1,691,000	17,000
2017/2018	4,000	2,182,000
Prior	2,181,000	31,000
Revolving Loans Amortized Cost Basis	68,078,000	77,528,000
Total loans and leases	77,066,000	86,572,000
Residential Mortgage.
Credit quality
2021/2022	242,485,000	1,304,978,000
2020/2021	1,287,330,000	753,668,000
2019/2020	725,918,000	363,415,000
2018/2019	339,678,000	266,368,000
2017/2018	243,470,000	332,041,000
Prior	1,313,531,000	1,062,135,000
Revolving Loans Amortized Cost Basis	909,001,000	867,295,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	10,512,000	10,075,000
Total loans and leases	5,071,925,000	4,959,975,000
Commercial and Industrial
Credit quality
2021/2022	165,757,000	637,126,000
2020/2021	494,676,000	142,497,000
2019/2020	109,426,000	237,293,000
2018/2019	197,106,000	106,699,000
2017/2018	96,629,000	32,409,000
Prior	174,090,000	177,825,000
Revolving Loans Amortized Cost Basis	653,797,000	711,028,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	32,053,000	42,222,000
Total loans and leases	1,923,534,000	2,087,099,000
Commercial and Industrial | Pass
Credit quality
2021/2022	158,853,000	623,098,000
2020/2021	483,473,000	129,665,000
2019/2020	98,061,000	223,388,000
2018/2019	184,897,000	88,409,000
2017/2018	79,810,000	29,380,000
Prior	166,075,000	168,591,000
Revolving Loans Amortized Cost Basis	594,007,000	644,947,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	31,048,000	40,193,000
Total loans and leases	1,796,224,000	1,947,671,000
Commercial and Industrial | Special mention
Credit quality
2021/2022	2,876,000	397,000
2020/2021	356,000	4,382,000
2019/2020	3,898,000	4,213,000
2018/2019	3,983,000	12,552,000
2017/2018	52,000	974,000
Prior	5,594,000	5,313,000
Revolving Loans Amortized Cost Basis	1,601,000	4,804,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	867,000	986,000
Total loans and leases	19,227,000	33,621,000
Commercial and Industrial | Substandard
Credit quality
2021/2022		354,000
2020/2021	337,000	1,380,000
2019/2020	1,296,000	1,951,000
2018/2019	1,776,000	1,285,000
2017/2018	13,251,000	60,000
Prior	757,000	3,551,000
Revolving Loans Amortized Cost Basis	15,877,000	17,893,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	138,000	1,043,000
Total loans and leases	33,432,000	27,517,000
Commercial and Industrial | Other Indicator
Credit quality
2021/2022	4,028,000	13,277,000
2020/2021	10,510,000	7,070,000
2019/2020	6,171,000	7,741,000
2018/2019	6,450,000	4,453,000
2017/2018	3,516,000	1,995,000
Prior	1,664,000	370,000
Revolving Loans Amortized Cost Basis	42,312,000	43,384,000
Total loans and leases	74,651,000	78,290,000
Commercial real estate
Credit quality
2021/2022	240,807,000	693,370,000
2020/2021	682,346,000	338,140,000
2019/2020	351,893,000	582,386,000
2018/2019	571,632,000	496,985,000
2017/2018	474,129,000	440,863,000
Prior	1,345,997,000	986,450,000
Revolving Loans Amortized Cost Basis	78,424,000	86,538,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	14,752,000	14,891,000
Total loans and leases	3,759,980,000	3,639,623,000
Commercial real estate | Pass
Credit quality
2021/2022	240,807,000	693,370,000
2020/2021	682,346,000	338,140,000
2019/2020	351,893,000	533,887,000
2018/2019	523,735,000	487,739,000
2017/2018	471,899,000	415,186,000
Prior	1,291,495,000	940,732,000
Revolving Loans Amortized Cost Basis	77,724,000	78,479,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	14,752,000	14,891,000
Total loans and leases	3,654,651,000	3,502,424,000
Commercial real estate | Special mention
Credit quality
2019/2020		48,499,000
2018/2019	47,897,000	7,470,000
2017/2018	473,000	25,513,000
Prior	39,064,000	30,255,000
Revolving Loans Amortized Cost Basis	696,000	7,600,000
Total loans and leases	88,130,000	119,337,000
Commercial real estate | Substandard
Credit quality
2018/2019		1,776,000
2017/2018	1,757,000	164,000
Prior	15,280,000	15,303,000
Revolving Loans Amortized Cost Basis	4,000	459,000
Total loans and leases	17,041,000	17,702,000
Commercial real estate | Other Indicator
Credit quality
Prior	158,000	160,000
Total loans and leases	158,000	160,000
Construction
Credit quality
2021/2022	14,031,000	181,393,000
2020/2021	197,577,000	116,642,000
2019/2020	124,300,000	214,875,000
2018/2019	139,410,000	160,689,000
2017/2018	117,903,000	65,454,000
Prior	94,787,000	51,264,000
Revolving Loans Amortized Cost Basis	20,292,000	23,652,000
Total loans and leases	708,300,000	813,969,000
Construction | Pass
Credit quality
2021/2022	6,160,000	154,558,000
2020/2021	167,645,000	107,767,000
2019/2020	118,526,000	210,314,000
2018/2019	136,209,000	155,311,000
2017/2018	112,919,000	62,770,000
Prior	89,172,000	48,021,000
Revolving Loans Amortized Cost Basis	19,470,000	22,859,000
Total loans and leases	650,101,000	761,600,000
Construction | Special mention
Credit quality
2019/2020		244,000
2018/2019	244,000	707,000
2017/2018	705,000
Prior	353,000	356,000
Total loans and leases	1,302,000	1,307,000
Construction | Substandard
Credit quality
2018/2019		363,000
2017/2018	357,000
Prior	827,000	839,000
Total loans and leases	1,184,000	1,202,000
Construction | Other Indicator
Credit quality
2021/2022	7,871,000	26,835,000
2020/2021	29,932,000	8,875,000
2019/2020	5,774,000	4,317,000
2018/2019	2,957,000	4,308,000
2017/2018	3,922,000	2,684,000
Prior	4,435,000	2,048,000
Revolving Loans Amortized Cost Basis	822,000	793,000
Total loans and leases	55,713,000	49,860,000
Lease financing
Credit quality
2021/2022	3,913,000	34,481,000
2020/2021	32,453,000	63,622,000
2019/2020	60,134,000	49,882,000
2018/2019	47,181,000	9,776,000
2017/2018	8,840,000	16,033,000
Prior	70,649,000	57,600,000
Total loans and leases	223,170,000	231,394,000
Lease financing | Pass
Credit quality
2021/2022	3,913,000	33,980,000
2020/2021	31,974,000	60,650,000
2019/2020	57,192,000	48,236,000
2018/2019	45,698,000	9,449,000
2017/2018	8,813,000	15,009,000
Prior	69,286,000	57,130,000
Total loans and leases	216,876,000	224,454,000
Lease financing | Special mention
Credit quality
2021/2022		501,000
2020/2021	479,000	2,702,000
2019/2020	2,672,000	1,506,000
2018/2019	1,360,000	311,000
2017/2018	12,000	153,000
Prior	20,000
Total loans and leases	4,543,000	5,173,000
Lease financing | Substandard
Credit quality
2020/2021		270,000
2019/2020	270,000	140,000
2018/2019	123,000	16,000
2017/2018	15,000	871,000
Prior	1,343,000	470,000
Total loans and leases	1,751,000	1,767,000
Commercial Lending
Credit quality
2021/2022	424,508,000	1,546,370,000
2020/2021	1,407,052,000	660,901,000
2019/2020	645,753,000	1,084,436,000
2018/2019	955,329,000	774,149,000
2017/2018	697,501,000	554,759,000
Prior	1,685,523,000	1,273,139,000
Revolving Loans Amortized Cost Basis	752,513,000	821,218,000
Revolving Loans Converted to Term Loans Amortized Cost Basis	46,805,000	57,113,000
Total loans and leases	$ 6,614,984,000	$ 6,772,085,000