Loans and Allowance for Loan Losses - Summary of Internal Risk-rating Categories (Detail) $ in Thousands	Mar. 31, 2022 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
2022	$ 726,346
2021	2,662,343
2020	1,869,054
2019	1,257,668
2018	938,759
Prior	3,034,743
Revolving Loans	1,658,375
Revolving Loans Converted to Term Loans	10,481
Total	12,157,769
Commercial and industrial | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	117,534
2021	583,948
2020	502,547
2019	232,822
2018	165,737
Prior	702,576
Revolving Loans	559,882
Revolving Loans Converted to Term Loans	1,032
Total	2,866,078
Commercial and industrial | Pass | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	117,534
2021	566,764
2020	498,791
2019	231,968
2018	142,428
Prior	689,728
Revolving Loans	504,127
Revolving Loans Converted to Term Loans	686
Total	2,752,026
Commercial and industrial | Special Mention | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	886
2020	0
2019	514
2018	278
Prior	4,459
Revolving Loans	51,581
Revolving Loans Converted to Term Loans	0
Total	57,718
Commercial and industrial | Substandard | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	11,302
2020	3,756
2019	340
2018	23,031
Prior	8,275
Revolving Loans	790
Revolving Loans Converted to Term Loans	346
Total	47,840
Commercial and industrial | Doubtful | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	4,996
2020	0
2019	0
2018	0
Prior	114
Revolving Loans	3,384
Revolving Loans Converted to Term Loans	0
Total	8,494
Commercial and industrial | Loss | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	0
Commercial real estate | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	435,260
2021	845,463
2020	662,105
2019	682,353
2018	552,684
Prior	1,373,872
Revolving Loans	51,970
Revolving Loans Converted to Term Loans	3,478
Total	4,607,185
Commercial real estate | Pass | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	378,744
2021	845,405
2020	641,300
2019	676,903
2018	495,084
Prior	1,304,769
Revolving Loans	43,970
Revolving Loans Converted to Term Loans	3,478
Total	4,389,653
Commercial real estate | Special Mention | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	26,613
2021	0
2020	16,142
2019	3,796
2018	19,562
Prior	19,776
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	85,889
Commercial real estate | Substandard | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	29,903
2021	58
2020	4,663
2019	1,654
2018	38,038
Prior	49,327
Revolving Loans	8,000
Revolving Loans Converted to Term Loans	0
Total	131,643
Commercial real estate | Doubtful | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	0
Commercial real estate | Loss | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	0
Commercial construction | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	3,623
2021	124,777
2020	61,278
2019	39,600
2018	0
Prior	0
Revolving Loans	15,760
Revolving Loans Converted to Term Loans	0
Total	245,038
Commercial construction | Pass | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	3,623
2021	124,777
2020	59,181
2019	32,857
2018	0
Prior	0
Revolving Loans	15,760
Revolving Loans Converted to Term Loans	0
Total	236,198
Commercial construction | Special Mention | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	2,097
2019	0
2018	0
Prior	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	2,097
Commercial construction | Substandard | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	6,743
2018	0
Prior	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	6,743
Commercial construction | Doubtful | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	0
Commercial construction | Loss | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	0
Business Banking | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	57,055
2021	312,601
2020	205,562
2019	156,322
2018	77,086
Prior	309,992
Revolving Loans	80,934
Revolving Loans Converted to Term Loans	4,116
Total	1,203,668
Business Banking | Pass | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	54,881
2021	309,961
2020	200,726
2019	141,974
2018	69,341
Prior	285,849
Revolving Loans	77,782
Revolving Loans Converted to Term Loans	3,436
Total	1,143,950
Business Banking | Special Mention | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	2,174
2021	2,176
2020	3,219
2019	9,152
2018	7,181
Prior	14,498
Revolving Loans	1,908
Revolving Loans Converted to Term Loans	0
Total	40,308
Business Banking | Substandard | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	464
2020	1,617
2019	4,993
2018	564
Prior	9,542
Revolving Loans	1,244
Revolving Loans Converted to Term Loans	680
Total	19,104
Business Banking | Doubtful | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	203
2018	0
Prior	103
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	306
Business Banking | Loss | Commercial Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	0
Residential real estate | Residential Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	81,889
2021	742,659
2020	407,917
2019	113,759
2018	80,617
Prior	519,001
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	1,945,842
Residential real estate | Residential Portfolio Segment | Current and accruing
Financing Receivable, Credit Quality Indicator [Line Items]
2022	81,889
2021	740,106
2020	406,401
2019	112,976
2018	78,320
Prior	505,432
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	1,925,124
Residential real estate | Residential Portfolio Segment | 30-89 days past due and accruing
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	2,553
2020	1,387
2019	201
2018	1,513
Prior	6,808
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	12,462
Residential real estate | Residential Portfolio Segment | Accruing loans past 90 days due
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	0
Residential real estate | Residential Portfolio Segment | Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	129
2019	582
2018	784
Prior	6,761
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	8,256
Consumer home equity | Consumer Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	15,321
2021	12,825
2020	7,008
2019	7,127
2018	28,045
Prior	95,037
Revolving Loans	934,534
Revolving Loans Converted to Term Loans	1,855
Total	1,101,752
Consumer home equity | Consumer Portfolio Segment | Current and accruing
Financing Receivable, Credit Quality Indicator [Line Items]
2022	15,321
2021	12,792
2020	6,903
2019	6,448
2018	26,582
Prior	91,599
Revolving Loans	929,383
Revolving Loans Converted to Term Loans	1,788
Total	1,090,816
Consumer home equity | Consumer Portfolio Segment | 30-89 days past due and accruing
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	33
2020	31
2019	0
2018	170
Prior	1,490
Revolving Loans	2,004
Revolving Loans Converted to Term Loans	67
Total	3,795
Consumer home equity | Consumer Portfolio Segment | Accruing loans past 90 days due
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	0
Consumer home equity | Consumer Portfolio Segment | Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	74
2019	679
2018	1,293
Prior	1,948
Revolving Loans	3,147
Revolving Loans Converted to Term Loans	0
Total	7,141
Other Consumer | Consumer Portfolio Segment
Financing Receivable, Credit Quality Indicator [Line Items]
2022	15,664
2021	40,070
2020	22,637
2019	25,685
2018	34,590
Prior	34,265
Revolving Loans	15,295
Revolving Loans Converted to Term Loans	0
Total	188,206
Other Consumer | Consumer Portfolio Segment | Current and accruing
Financing Receivable, Credit Quality Indicator [Line Items]
2022	15,652
2021	39,868
2020	22,534
2019	25,531
2018	33,967
Prior	33,664
Revolving Loans	15,295
Revolving Loans Converted to Term Loans	0
Total	186,511
Other Consumer | Consumer Portfolio Segment | 30-89 days past due and accruing
Financing Receivable, Credit Quality Indicator [Line Items]
2022	12
2021	107
2020	76
2019	117
2018	449
Prior	429
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	1,190
Other Consumer | Consumer Portfolio Segment | Accruing loans past 90 days due
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	0
Other Consumer | Consumer Portfolio Segment | Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
2022	0
2021	95
2020	27
2019	37
2018	174
Prior	172
Revolving Loans	0
Revolving Loans Converted to Term Loans	0
Total	$ 505