Securities Available for Sale - Amortized cost/fair value (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 117,545	$ 287,293
Gross Unrealized Gains	86	91
Gross Unrealized Losses	(58)	(247)
Fair Value	117,573	287,137
Asset-backed senior securities related to Company-sponsored securitizations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	36,953
Gross Unrealized Gains	73
Gross Unrealized Losses	(6)
Fair Value	37,020
Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	24,758	27,501
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	24,758	27,501
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	16,268	181,359
Gross Unrealized Gains	1	63
Gross Unrealized Losses	(11)	(199)
Fair Value	16,258	181,223
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,843	25,369
Gross Unrealized Gains	1	4
Gross Unrealized Losses	(1)	(9)
Fair Value	14,843	25,364
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	14,665	20,164
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	14,665	20,164
U.S. agency securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		19,602
Gross Unrealized Gains		21
Gross Unrealized Losses		0
Fair Value		19,623
U.S. Treasury securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		2,493
Gross Unrealized Gains		3
Gross Unrealized Losses		0
Fair Value		2,496
Other securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		10,805
Gross Unrealized Gains		0
Gross Unrealized Losses		(39)
Fair Value		10,766
Asset-backed subordinated residual certificates related to Company-sponsored securitizations and CLUB Certificate transactions
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,058
Gross Unrealized Gains	11
Gross Unrealized Losses	(40)
Fair Value	10,029
Asset-backed securities related to Company-sponsored securitizations
Schedule of Available-for-sale Securities [Line Items]
Fair Value	45,300
Securitizations
Schedule of Available-for-sale Securities [Line Items]
Fair Value	47,049
Level 3 Inputs
Schedule of Available-for-sale Securities [Line Items]
Fair Value	10,029	0
Level 3 Inputs \| Asset-backed senior securities related to Company-sponsored securitizations
Schedule of Available-for-sale Securities [Line Items]
Fair Value	0
Level 3 Inputs \| Certificates of deposit
Schedule of Available-for-sale Securities [Line Items]
Fair Value	0	0
Level 3 Inputs \| Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	0	0
Level 3 Inputs \| Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	0	0
Level 3 Inputs \| Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Fair Value	0	0
Level 3 Inputs \| U.S. agency securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value		0
Level 3 Inputs \| U.S. Treasury securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value		0
Level 3 Inputs \| Other securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value		$ 0
Level 3 Inputs \| Asset-backed subordinated residual certificates related to Company-sponsored securitizations and CLUB Certificate transactions
Schedule of Available-for-sale Securities [Line Items]
Fair Value	10,029
Level 3 Inputs \| Subordinated residual certificates \| Securitizations
Schedule of Available-for-sale Securities [Line Items]
Fair Value	$ 10,000

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562

+ Details

Name:	us-gaap_AvailableForSaleSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

+ Details

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

- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAmortizedCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=lc_AssetbackedSeniorSecuritiesRelatedtoCompanysponsoredSecuritizationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CertificatesOfDepositMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CommercialPaperMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_OtherDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=lc_AssetbackedSubordinatedResidualCertificatesRelatedtoCompanysponsoredSecuritizationsandCLUBCertificateTransactionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=lc_AssetbackedSecuritiesSecuritizedLoansandReceivablesSubjecttoRestrictionsonTransferMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_AssetBackedSecuritiesSecuritizedLoansAndReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=lc_SubordinatedResidualCertificatesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: