Loans and Leases Held for Investment, Net of Allowance For Loan and Lease Losses - Allowance For Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan and lease losses, beginning of period	$ 243,260	$ 71,081	$ 0	$ 144,389	$ 0
Credit loss expense for loans and leases held for investment	82,599	37,133		204,880	95,662
Initial allowance for PCD loans acquired during the period				0	12,440
Charge-offs	(23,728)	(4,336)		(48,669)	(4,582)
Recoveries	1,070	858		2,601	1,216
Allowance for loan and lease losses, end of period	303,201	104,736		303,201	104,736
Radius Bancorp, Inc.
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Credit loss expense for loans and leases held for investment			6,900
Unfunded Loan Commitment
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Reserve for unfunded lending commitments, beginning of period	2,025	390	0	1,231	0
Credit loss expense for unfunded lending commitments	140	887		934	1,277
Reserve for unfunded lending commitments, end of period	2,165	1,277		2,165	1,277
Unfunded Loan Commitment, Commitments To Extend Credit
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Reserve for unfunded lending commitments, beginning of period				110,800
Reserve for unfunded lending commitments, end of period	144,000	115,500		144,000	115,500
Consumer Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan and lease losses, beginning of period	228,184	54,058	0	128,812	0
Credit loss expense for loans and leases held for investment	81,935	37,695		203,967	91,194
Initial allowance for PCD loans acquired during the period				0	603
Charge-offs	(22,944)	(3,142)		(46,668)	(3,232)
Recoveries	963	20		2,027	66
Allowance for loan and lease losses, end of period	288,138	88,631		288,138	88,631
Consumer Portfolio Segment \| Unfunded Loan Commitment
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Reserve for unfunded lending commitments, beginning of period	136	0	0	0	0
Credit loss expense for unfunded lending commitments	(78)	50		58	50
Reserve for unfunded lending commitments, end of period	58	50		58	50
Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for loan and lease losses, beginning of period	15,076	17,023	0	15,577	0
Credit loss expense for loans and leases held for investment	664	(562)		913	4,468
Initial allowance for PCD loans acquired during the period				0	11,837
Charge-offs	(784)	(1,194)		(2,001)	(1,350)
Recoveries	107	838		574	1,150
Allowance for loan and lease losses, end of period	15,063	16,105		15,063	16,105
Commercial Portfolio Segment \| Unfunded Loan Commitment
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Reserve for unfunded lending commitments, beginning of period	1,889	390	$ 0	1,231	0
Credit loss expense for unfunded lending commitments	218	837		876	1,227
Reserve for unfunded lending commitments, end of period	$ 2,107	$ 1,227		$ 2,107	$ 1,227

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124255206&loc=SL82895884-210446

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Amount, excluding accrued interest, of increase in allowance for credit loss on financing receivable from recovery. Excludes net investment in lease.

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Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

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Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. Excludes net investment in lease.

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Amount, excluding accrued interest, of allowance for credit loss at acquisition date of financing receivable purchased with credit deterioration. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 19
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919265-210447

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=121611286&loc=d3e11927-110247

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124255206&loc=SL82919202-210446

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Amount of expense (reversal of expense) for expected credit loss for off-balance sheet credit exposure. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

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Amount of credit loss expense (reversal of expense) for financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(11))
-URI https://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

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