Allowance for Credit Losses - Summary of loans in Accrual and Nonaccrual Status (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 92,040,032	$ 97,628,892
30-89 Days Past Due	845,930	662,439
Accruing Loans Past Due 90 Days or More	963,399	859,208
Nonaccrual	2,060,083	1,893,299
Loans and leases, net of unearned discount	92,912,452	98,535,867
Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	16,234,904	16,963,561
Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,199,887	1,387,378
Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	239,561	200,406
Accruing Loans Past Due 90 Days or More	920,080	792,888
Nonaccrual	355,858	365,729
Loans and leases, net of unearned discount	14,810,371	15,123,859
Residential [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Nonaccrual	263	200
Loans and leases, net of unearned discount	72,572	72,094
Residential Limited Documentation [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	16,666	19,687
Nonaccrual	122,888	147,170
Loans and leases, net of unearned discount	1,264,074	1,629,134
Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	15,486	24,329
Nonaccrual	70,488	79,392
Loans and leases, net of unearned discount	3,562,591	3,985,606
Home Equity Lines and Loans [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	346	939
Nonaccrual	4,951	5,752
Loans and leases, net of unearned discount	2,353,576	2,576,312
Home Equity Lines and Loans [Member] | Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	14,421	22,242
Nonaccrual	59,787	67,492
Loans and leases, net of unearned discount	1,156,983	1,341,919
Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	40,544	47,161
Nonaccrual	27,811	25,519
Loans and leases, net of unearned discount	8,053,528	7,075,323
Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	40,064	55,498
Nonaccrual	34,037	39,404
Loans and leases, net of unearned discount	4,678,873	4,102,251
Other [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	12,223	17,561
Accruing Loans Past Due 90 Days or More	3,302	4,581
Nonaccrual	44,289	38,231
Loans and leases, net of unearned discount	1,679,961	1,407,241
Other [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	1,908	10,594
Accruing Loans Past Due 90 Days or More		4,207
Nonaccrual	40,807	35,044
Loans and leases, net of unearned discount	1,190,811	977,062
Other [Member] | Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	434	481
Nonaccrual	129	148
Loans and leases, net of unearned discount	2,068	2,485
Current [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	89,043,040	95,120,921
Current [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	13,294,872	13,764,836
Current [Member] | Residential [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	72,309	71,894
Current [Member] | Residential Limited Documentation [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,124,520	1,462,277
Current [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,476,617	3,881,885
Current [Member] | Home Equity Lines and Loans [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,348,279	2,569,621
Current [Member] | Home Equity Lines and Loans [Member] | Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,082,775	1,252,185
Current [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	7,985,173	7,002,643
Current [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	4,604,772	4,007,349
Current [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,620,147	1,346,868
Current [Member] | Other [Member] | Revolving Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,148,096	927,217
Current [Member] | Other [Member] | Revolving Loans Converted to Term Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,505	1,856
Term Loans 2021 [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	18,817,411
Term Loans 2021 [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	15,245
Accruing Loans Past Due 90 Days or More	10,924
Nonaccrual	3,359
Loans and leases, net of unearned discount	3,086,646
Term Loans 2021 [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	304
Term Loans 2021 [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	5,929
Nonaccrual	1,341
Loans and leases, net of unearned discount	2,897,381
Term Loans 2021 [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	8,508
Nonaccrual	1,588
Loans and leases, net of unearned discount	2,230,157
Term Loans 2021 [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	2,937
Nonaccrual	2,051
Loans and leases, net of unearned discount	249,334
Term Loans 2021 [Member] | Current [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	3,057,118
Term Loans 2021 [Member] | Current [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	304
Term Loans 2021 [Member] | Current [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,890,111
Term Loans 2021 [Member] | Current [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,220,061
Term Loans 2021 [Member] | Current [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	244,346
Term Loans 2020 [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	12,376,366	20,949,019
Term Loans 2020 [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	12,535	13,496
Accruing Loans Past Due 90 Days or More	100,581	579
Nonaccrual	19,858	3,133
Loans and leases, net of unearned discount	1,805,064	2,740,070
Term Loans 2020 [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	777	773
Term Loans 2020 [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	8,912	9,548
Nonaccrual	4,646	1,854
Loans and leases, net of unearned discount	2,101,900	2,807,761
Term Loans 2020 [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	6,615	6,461
Nonaccrual	4,390	1,615
Loans and leases, net of unearned discount	1,108,689	1,603,712
Term Loans 2020 [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	404	1,879
Nonaccrual	326	1,493
Loans and leases, net of unearned discount	97,675	163,796
Term Loans 2020 [Member] | Current [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,672,090	2,722,862
Term Loans 2020 [Member] | Current [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	777	773
Term Loans 2020 [Member] | Current [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,088,342	2,796,359
Term Loans 2020 [Member] | Current [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,097,684	1,595,636
Term Loans 2020 [Member] | Current [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	96,945	160,424
Term Loans 2019 [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	12,286,933	15,628,942
Term Loans 2019 [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	9,886	7,781
Accruing Loans Past Due 90 Days or More	28,512	15,234
Nonaccrual	7,119	14,439
Loans and leases, net of unearned discount	1,121,413	1,453,713
Term Loans 2019 [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	2,793	3,983
Term Loans 2019 [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	8,317	11,255
Nonaccrual	4,871	3,883
Loans and leases, net of unearned discount	1,281,117	1,766,904
Term Loans 2019 [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	8,936	14,140
Nonaccrual	7,847	7,144
Loans and leases, net of unearned discount	678,783	1,128,066
Term Loans 2019 [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	472	1,130
Nonaccrual	326	492
Loans and leases, net of unearned discount	74,384	139,239
Term Loans 2019 [Member] | Current [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,075,896	1,416,259
Term Loans 2019 [Member] | Current [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	2,793	3,983
Term Loans 2019 [Member] | Current [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,267,929	1,751,766
Term Loans 2019 [Member] | Current [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	662,000	1,106,782
Term Loans 2019 [Member] | Current [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	73,586	137,617
Term Loans 2018 [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	7,895,140	10,466,749
Term Loans 2018 [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	6,132	7,258
Accruing Loans Past Due 90 Days or More	31,996	38,145
Nonaccrual	4,577	5,183
Loans and leases, net of unearned discount	508,745	669,322
Term Loans 2018 [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	21
Loans and leases, net of unearned discount	1,751	1,591
Term Loans 2018 [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	5,074	8,519
Nonaccrual	4,918	4,072
Loans and leases, net of unearned discount	656,875	920,186
Term Loans 2018 [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	7,161	12,542
Nonaccrual	7,867	10,788
Loans and leases, net of unearned discount	356,683	652,668
Term Loans 2018 [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	255	577
Nonaccrual	193	339
Loans and leases, net of unearned discount	24,872	54,618
Term Loans 2018 [Member] | Current [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	466,040	618,736
Term Loans 2018 [Member] | Current [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,730	1,591
Term Loans 2018 [Member] | Current [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	646,883	907,595
Term Loans 2018 [Member] | Current [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	341,655	629,338
Term Loans 2018 [Member] | Current [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	24,424	53,702
Term Loans 2017 [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	5,558,871	7,893,838
Term Loans 2017 [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	33,097	13,477
Accruing Loans Past Due 90 Days or More	205,318	212,818
Nonaccrual	5,890	6,408
Loans and leases, net of unearned discount	1,282,263	1,550,797
Term Loans 2017 [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	1,944	2,016
Term Loans 2017 [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	5,189	6,638
Nonaccrual	4,039	4,194
Loans and leases, net of unearned discount	455,096	640,983
Term Loans 2017 [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	5,715	12,899
Nonaccrual	6,882	10,061
Loans and leases, net of unearned discount	224,371	463,564
Term Loans 2017 [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	101	2,301
Nonaccrual	104	183
Loans and leases, net of unearned discount	17,129	35,040
Term Loans 2017 [Member] | Current [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,037,958	1,318,094
Term Loans 2017 [Member] | Current [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,944	2,016
Term Loans 2017 [Member] | Current [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	445,868	630,151
Term Loans 2017 [Member] | Current [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	211,774	440,604
Term Loans 2017 [Member] | Current [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	16,924	32,556
Term Loans Prior Period [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount	18,542,940	19,233,367
Term Loans Prior Period [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	162,666	150,447
Accruing Loans Past Due 90 Days or More	542,749	480,308
Nonaccrual	314,792	333,466
Loans and leases, net of unearned discount	6,933,668	7,862,977
Term Loans Prior Period [Member] | Residential Limited Documentation [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	16,666	19,687
Nonaccrual	122,888	147,170
Loans and leases, net of unearned discount	1,264,074	1,629,134
Term Loans Prior Period [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	698	1,148
Nonaccrual	5,750	6,148
Loans and leases, net of unearned discount	44,463	58,850
Term Loans Prior Period [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	7,123	8,263
Nonaccrual	7,996	8,783
Loans and leases, net of unearned discount	661,159	581,404
Term Loans Prior Period [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	3,129	3,083
Nonaccrual	5,463	3,805
Loans and leases, net of unearned discount	80,190	70,860
Term Loans Prior Period [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due	5,712	557
Accruing Loans Past Due 90 Days or More	3,302	374
Nonaccrual	353	501
Loans and leases, net of unearned discount	23,688	30,402
Term Loans Prior Period [Member] | Current [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	5,913,461	6,898,756
Term Loans Prior Period [Member] | Current [Member] | Residential Limited Documentation [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	1,124,520	1,462,277
Term Loans Prior Period [Member] | Current [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	38,015	51,554
Term Loans Prior Period [Member] | Current [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	646,040	564,358
Term Loans Prior Period [Member] | Current [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	71,598	63,972
Term Loans Prior Period [Member] | Current [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans	$ 14,321	28,970
Term Loans 2016 [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount		6,013,013
Term Loans 2016 [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due		7,947
Accruing Loans Past Due 90 Days or More		45,804
Nonaccrual		2,900
Loans and leases, net of unearned discount		774,886
Term Loans 2016 [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases, net of unearned discount		162
Term Loans 2016 [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due		2,938
Nonaccrual		2,733
Loans and leases, net of unearned discount		358,085
Term Loans 2016 [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due		6,373
Nonaccrual		5,991
Loans and leases, net of unearned discount		183,381
Term Loans 2016 [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
30-89 Days Past Due		42
Nonaccrual		31
Loans and leases, net of unearned discount		4,599
Term Loans 2016 [Member] | Current [Member] | Residential [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		718,235
Term Loans 2016 [Member] | Current [Member] | Home Equity Lines and Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		162
Term Loans 2016 [Member] | Current [Member] | Recreational Finance [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		352,414
Term Loans 2016 [Member] | Current [Member] | Automobile [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		171,017
Term Loans 2016 [Member] | Current [Member] | Other [Member]
Financing Receivable Recorded Investment [Line Items]
Total loans		$ 4,526