Allowance for Credit Losses - Loan Balances by Year of Origination and Performing and Nonperforming Status (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	$ 1,380,130	$ 1,360,684
Year two	772,783	1,214,746
Year three	961,071	831,734
Year four	606,970	565,201
Year five	431,724	610,556
More than five years	1,591,979	1,572,826
Revolving	1,226,925	1,041,199
Revolving-Term	28,408	28,914
Total	6,999,990	7,225,860
Performing TDRs
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	1,380,089	1,360,654
Year two	771,819	1,196,491
Year three	940,641	827,625
Year four	602,938	543,253
Year five	421,125	586,622
More than five years	1,564,501	1,496,135
Revolving	1,224,949	1,040,544
Revolving-Term	27,638	27,762
Total	6,933,699	7,079,086
Nonperforming TDRs
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	41	30
Year two	964	18,254
Year three	20,430	4,108
Year four	4,032	21,948
Year five	10,599	23,934
More than five years	27,478	76,691
Revolving	1,976	654
Revolving-Term	770	1,153
Total	66,291	146,774
Commercial | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	385,347	334,086
Year two	317,359	476,203
Year three	468,720	417,944
Year four	334,743	320,140
Year five	266,019	415,184
More than five years	881,391	780,560
Revolving	36,948	47,830
Revolving-Term	0	0
Total	2,690,528	2,791,947
Commercial | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	437,529	457,828
Year two	126,371	215,457
Year three	134,417	145,290
Year four	86,912	82,249
Year five	41,422	28,488
More than five years	136,470	221,609
Revolving	550,402	408,631
Revolving-Term	0	0
Total	1,513,523	1,559,552
Commercial | Commercial construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	142,321	132,813
Year two	110,562	230,907
Year three	113,532	63,535
Year four	16,838	2,921
Year five	989	6,346
More than five years	10,477	16,777
Revolving	30,036	12,778
Revolving-Term	0	0
Total	424,755	466,077
Commercial | Business banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	257,409	296,357
Year two	108,048	156,473
Year three	144,976	128,250
Year four	115,228	91,363
Year five	81,889	82,202
More than five years	318,735	298,779
Revolving	108,230	105,549
Revolving-Term	1,179	1,094
Total	1,135,693	1,160,067
Commercial | Performing TDRs | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	385,347	334,086
Year two	317,359	459,799
Year three	461,613	417,944
Year four	332,482	313,465
Year five	259,723	394,972
More than five years	865,567	722,782
Revolving	36,948	47,830
Revolving-Term	0	0
Total	2,659,039	2,690,879
Commercial | Performing TDRs | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	437,529	457,828
Year two	126,371	214,144
Year three	123,944	143,706
Year four	86,852	69,411
Year five	38,540	28,426
More than five years	136,427	220,701
Revolving	548,622	408,350
Revolving-Term	0	0
Total	1,498,285	1,542,566
Commercial | Performing TDRs | Commercial construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	142,321	132,813
Year two	110,562	230,907
Year three	111,445	63,535
Year four	16,838	2,921
Year five	989	6,346
More than five years	10,093	16,393
Revolving	30,036	12,778
Revolving-Term	0	0
Total	422,284	465,692
Commercial | Performing TDRs | Business banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	257,368	296,327
Year two	107,984	156,164
Year three	144,689	126,432
Year four	113,820	90,414
Year five	81,195	80,106
More than five years	311,673	286,970
Revolving	108,202	105,494
Revolving-Term	1,122	1,037
Total	1,126,052	1,142,944
Commercial | Nonperforming TDRs | Commercial real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Year two		16,404
Year three	7,107	0
Year four	2,261	6,675
Year five	6,296	20,212
More than five years	15,824	57,778
Revolving	0	0
Revolving-Term	0	0
Total	31,488	101,070
Commercial | Nonperforming TDRs | Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Year two	0	1,313
Year three	10,473	1,584
Year four	60	12,838
Year five	2,882	62
More than five years	43	908
Revolving	1,780	281
Revolving-Term	0	0
Total	15,239	16,985
Commercial | Nonperforming TDRs | Commercial construction
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Year two	0	0
Year three	2,087	0
Year four	0	0
Year five	0	0
More than five years	384	384
Revolving	0	0
Revolving-Term	0	0
Total	2,471	384
Commercial | Nonperforming TDRs | Business banking
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	41	30
Year two	64	309
Year three	287	1,818
Year four	1,408	949
Year five	694	2,096
More than five years	7,062	11,809
Revolving	28	55
Revolving-Term	57	57
Total	9,641	17,123
Consumer | Consumer real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	137,465	120,736
Year two	100,995	122,544
Year three	92,165	69,931
Year four	50,156	65,133
Year five	40,384	76,254
More than five years	238,462	251,047
Revolving	443,406	439,020
Revolving-Term	24,552	22,667
Total	1,127,585	1,167,332
Consumer | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	20,059	18,864
Year two	9,448	13,162
Year three	7,261	6,784
Year four	3,093	3,395
Year five	1,021	2,082
More than five years	6,444	4,054
Revolving	57,903	27,391
Revolving-Term	2,677	5,153
Total	107,906	80,885
Consumer | Performing TDRs | Consumer real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	137,465	120,736
Year two	100,253	122,315
Year three	91,689	69,225
Year four	49,853	63,647
Year five	39,657	74,690
More than five years	234,297	245,331
Revolving	443,238	438,702
Revolving-Term	23,839	21,572
Total	1,120,291	1,156,216
Consumer | Performing TDRs | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	20,059	18,864
Year two	9,290	13,162
Year three	7,261	6,784
Year four	3,093	3,395
Year five	1,021	2,082
More than five years	6,444	3,958
Revolving	57,903	27,391
Revolving-Term	2,677	5,153
Total	107,748	80,789
Consumer | Nonperforming TDRs | Consumer real estate
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Year two	742	229
Year three	476	706
Year four	303	1,486
Year five	727	1,564
More than five years	4,165	5,716
Revolving	168	318
Revolving-Term	713	1,096
Total	7,294	11,116
Consumer | Nonperforming TDRs | Other consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Current fiscal year	0	0
Year two	158	0
Year three	0	0
Year four	0	0
Year five	0	0
More than five years	0	96
Revolving	0	0
Revolving-Term	0	0
Total	$ 158	$ 96