Securities Available for Sale - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2021
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, beginning	$ (592)	$ (18,736)
Reversal of credit loss expense	496	3,288
Reversal of allowance arising from PCD financial assets		15,352
Allowance for credit losses, ending	(96)	(96)
CLUB Certificate asset-backed securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, beginning	(40)	(4,190)
Reversal of credit loss expense	40	236
Reversal of allowance arising from PCD financial assets		3,954
Allowance for credit losses, ending	0	0
Asset-backed subordinated securities
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses, beginning	(552)	(14,546)
Reversal of credit loss expense	456	3,052
Reversal of allowance arising from PCD financial assets		11,398
Allowance for credit losses, ending	$ (96)	$ (96)

Debt Securities, Available-for-Sale, Allowance for Credit Loss, Purchased with Credit Deterioration, Decrease

No definition available.

Name:	lc_DebtSecuritiesAvailableForSaleAllowanceForCreditLossPurchasedWithCreditDeteriorationDecrease
Namespace Prefix:	lc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase in allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), from recovery.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (h)
-URI https://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount excluding accrued interest, of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_FinancialInstrumentAxis=lc_CLUBCertificateAssetbackedSecuritiesMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

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