Loans and Allowance for Credit Losses - Rollforward of Allowance for Credit/Loan Losses by Portfolio Segment (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	$ 205,773	$ 191,146	$ 218,583	$ 101,788
Charge-offs	(33,573)	(6,358)	(40,175)	(16,122)
Recoveries	5,199	817	6,491	2,909
Provision	26,000	18,000	18,500	106,000
Ending balance - ACL	203,399	203,605	203,399	203,605
Beginning balance - ACL on off-balance sheet	5,588	2,978	5,588	2,978
Provision	(2,000)	3,500	(2,000)	3,500
Ending balance - ACL on off-balance sheet	3,588	6,478	3,588	6,478
ASU 2016-13 Adjustment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
ASU 2016-13 adjustment				9,030
Commercial and Industrial Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	119,568	122,532	122,700	63,313
Charge-offs	(2)	(1,121)	(4,719)	(2,436)
Recoveries	3,635	241	3,761	1,717
Provision	(5,080)	(7,042)	(3,621)	48,339
Ending balance - ACL	118,121	114,610	118,121	114,610
Beginning balance - ACL on off-balance sheet	3,859	2,263	3,859	2,263
Provision	(1,515)	3,154	(1,515)	3,154
Ending balance - ACL on off-balance sheet	2,344	5,417	2,344	5,417
Commercial and Industrial Portfolio [Member] \| ASU 2016-13 Adjustment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
ASU 2016-13 adjustment				3,677
Specialty Lending Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	4,673	3,549	5,219	2,545
Charge-offs	(31,945)		(31,945)
Recoveries	36		151
Provision	33,137	(2,620)	32,476	(1,764)
Ending balance - ACL	5,901	929	5,901	929
Beginning balance - ACL on off-balance sheet	287	53	287	53
Provision	(74)	28	(74)	28
Ending balance - ACL on off-balance sheet	213	81	213	81
Specialty Lending Portfolio [Member] \| ASU 2016-13 Adjustment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
ASU 2016-13 adjustment				148
Commercial Real Estate Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	60,043	35,395	61,931	15,951
Charge-offs		(2,858)		(8,920)
Recoveries	838	55	1,347	76
Provision	(4,147)	23,242	(6,544)	47,801
Ending balance - ACL	56,734	55,834	56,734	55,834
Beginning balance - ACL on off-balance sheet	447	257	447	257
Provision	(121)	146	(121)	146
Ending balance - ACL on off-balance sheet	326	403	326	403
Commercial Real Estate Portfolio [Member] \| ASU 2016-13 Adjustment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
ASU 2016-13 adjustment				926
Consumer Real Estate Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	4,183	4,177	6,586	2,623
Charge-offs	(10)	(206)	(86)	(219)
Recoveries	54	34	113	48
Provision	1,580	1,947	(806)	3,348
Ending balance - ACL	5,807	5,952	5,807	5,952
Beginning balance - ACL on off-balance sheet	145	102	145	102
Provision	(3)	212	(3)	212
Ending balance - ACL on off-balance sheet	142	314	142	314
Consumer Real Estate Portfolio [Member] \| ASU 2016-13 Adjustment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
ASU 2016-13 adjustment				152
Consumer Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	603	1,127	1,480	543
Charge-offs	(139)	(158)	(248)	(406)
Recoveries	64	118	87	215
Provision	329	519	(462)	1,223
Ending balance - ACL	857	1,606	857	1,606
Beginning balance - ACL on off-balance sheet	381	22	381	22
Provision	(173)	11	(173)	11
Ending balance - ACL on off-balance sheet	208	33	208	33
Consumer Portfolio [Member] \| ASU 2016-13 Adjustment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
ASU 2016-13 adjustment				31
Credit Cards Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	12,144	18,823	15,786	15,739
Charge-offs	(1,477)	(2,004)	(3,169)	(4,130)
Recoveries	572	369	1,014	853
Provision	504	2,397	(1,888)	6,209
Ending balance - ACL	11,743	19,585	11,743	19,585
Credit Cards Portfolio [Member] \| ASU 2016-13 Adjustment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
ASU 2016-13 adjustment				914
Leases and Other Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	1,600	2,308	2,271	1,074
Charge-offs		(11)	(8)	(11)
Recoveries			18
Provision	(200)	(513)	(881)	659
Ending balance - ACL	1,400	1,784	1,400	1,784
Beginning balance - ACL on off-balance sheet	414	211	414	211
Provision	(150)	(38)	(150)	(38)
Ending balance - ACL on off-balance sheet	264	173	264	173
Leases and Other Portfolio [Member] \| ASU 2016-13 Adjustment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
ASU 2016-13 adjustment				62
Total - Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	202,814	187,911	215,973	101,788
Charge-offs	(33,573)	(6,358)	(40,175)	(16,122)
Recoveries	5,199	817	6,491	2,909
Provision	26,123	17,930	18,274	105,815
Ending balance - ACL	200,563	200,300	200,563	200,300
Beginning balance - ACL on off-balance sheet	5,533	2,908	5,533	2,908
Provision	(2,036)	3,513	(2,036)	3,513
Ending balance - ACL on off-balance sheet	3,497	6,421	3,497	6,421
Total - Loans [Member] \| ASU 2016-13 Adjustment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
ASU 2016-13 adjustment				5,910
HTM [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning balance	2,959	3,235	2,610
Provision	(123)	70	226	185
Ending balance - ACL	2,836	3,305	2,836	3,305
Beginning balance - ACL on off-balance sheet	55	70	55	70
Provision	36	(13)	36	(13)
Ending balance - ACL on off-balance sheet	$ 91	$ 57	$ 91	57
HTM [Member] \| ASU 2016-13 Adjustment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
ASU 2016-13 adjustment				$ 3,120

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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

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