Allowance for Loan and Lease Losses, Provision For Loss Resulting From On-going Bankruptcy Proceedings

No definition available.

Name:	ladr_AllowanceforLoanandLeaseLossesProvisionForLossResultingFromOngoingBankruptcyProceedings
Namespace Prefix:	ladr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair Value Inputs, Direct Capitalization Rate

+ References

No definition available.

+ Details

Name:	ladr_FairValueInputsDirectCapitalizationRate
Namespace Prefix:	ladr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Financing Receivable, Equity Interest Not Subject To Dilution, Percentage

+ References

No definition available.

+ Details

Name:	ladr_FinancingReceivableEquityInterestNotSubjectToDilutionPercentage
Namespace Prefix:	ladr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Financing Receivable Recorded Investment 90 Days Past Due And Still Accruing Number of Contracts

+ References

No definition available.

+ Details

Name:	ladr_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruingNumberofContracts
Namespace Prefix:	ladr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans Receivable With Fixed Rates Of Interest, Percentage

+ References

No definition available.

+ Details

Name:	ladr_LoansReceivableWithFixedRatesOfInterestPercentage
Namespace Prefix:	ladr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Loans Receivable With Variable Rates Of Interest, Percentage

+ References

No definition available.

+ Details

Name:	ladr_LoansReceivableWithVariableRatesOfInterestPercentage
Namespace Prefix:	ladr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Loans Receivable with Variable Rates of Interest, Subject To Interest Rate Floors

+ References

No definition available.

+ Details

Name:	ladr_LoansReceivablewithVariableRatesofInterestSubjectToInterestRateFloors
Namespace Prefix:	ladr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of mortgage loans individually impaired.

+ References

No definition available.

+ Details

Name:	ladr_NumberOfMortgageLoansIndividuallyImpaired
Namespace Prefix:	ladr_
Data Type:	xbrli:integerItemType
Balance Type:	na
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:	srt_MortgageLoansOnRealEstateLineItems
Namespace Prefix:	srt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of financing receivable 90 days or more past due and still accruing.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5111-111524

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 55
-Paragraph 80
-URI http://asc.fasb.org/extlink&oid=118955255&loc=SL82922355-210448

+ Details

Name:	us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of financing receivable on nonaccrual status.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5111-111524

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 16
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919258-210447

+ Details

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

- Definition

Amount of loan with fixed rate of interest.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

+ Details

Name:	us-gaap_LoansReceivableWithFixedRatesOfInterest1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of loan with variable or adjustable rate of interest.

+ References

+ Details

Name:	us-gaap_LoansReceivableWithVariableRatesOfInterest1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of expense related to estimated loss from loan and lease transactions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

+ Details

Name:	us-gaap_ProvisionForLoanAndLeaseLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6378536&loc=d3e10092-111533

+ Details

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

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MortgageLoansOnRealEstateLoanTypeAxis=ladr_MortgageLoanReceivablesHeldForInvestmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CollateralAxis=ladr_TwoOfCompanyLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CollateralAxis=ladr_OneOfCompanyLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_SeriesAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_SeriesBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CollateralAxis=ladr_AssetSpecificReserveCompanyLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MortgageLoansOnRealEstateLoanTypeAxis=ladr_MortgageLoanReceivablesHeldForSaleMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MortgageLoansOnRealEstateLoanTypeAxis=ladr_NonPerformingLoansHeldForInvestmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

MORTGAGE LOAN RECEIVABLES - Additional Information (Details)		3 Months Ended			9 Months Ended
	Mar. 31, 2018 USD ($)	Sep. 30, 2019 USD ($) loan	Dec. 31, 2018 USD ($) loan	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) loan	Sep. 30, 2018 USD ($)
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Unamortized discounts included in mortgage loan receivables held for investment, at amortized cost		$ 100,000	$ 500,000		$ 100,000
Provision for loan losses		0		$ 10,300,000	600,000	$ 13,600,000
Loans nonaccrual status, amount		$ 37,161,000	$ 36,850,000		$ 37,161,000
Minimum
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Direct capitalization rate	4.70%				4.60%
Maximum
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number of mortgage loans impaired \| loan		3	3		3
Direct capitalization rate	5.00%				4.90%
Total mortgage loan receivables held for investment, net, at amortized cost
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loans receivable with variable rates of interest		$ 2,500,000,000	$ 2,500,000,000		$ 2,500,000,000
Loans receivable with variable rates of interest		78.40%	75.40%		78.40%
Loans receivable with variable rates of interest, subject to interest rate floors		100.00%	100.00%		100.00%
Total mortgage loan receivables held for investment, net, at amortized cost \| Two Of Company Loans
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Number or loans in default \| loan					2
Loans in default, carrying value		$ 26,900,000			$ 26,900,000
Loan reserve amount	$ 2,700,000
Total mortgage loan receivables held for investment, net, at amortized cost \| One Of Company Loans
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Provision for loan losses				10,000,000.0		$ 12,700,000
Loans in default, carrying value			$ 45,000,000.0
Total mortgage loan receivables held for investment, net, at amortized cost \| One Of Company Loans \| Series A
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loans in default, carrying value			35,000,000.0
Total mortgage loan receivables held for investment, net, at amortized cost \| One Of Company Loans \| Series B
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loans in default, carrying value			$ 10,000,000.0
Total mortgage loan receivables held for investment, net, at amortized cost \| One Of Company Loans \| Minimum
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Percentage of equity kicker not subject to investment			19.00%
Total mortgage loan receivables held for investment, net, at amortized cost \| One Of Company Loans \| Maximum
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Percentage of equity kicker not subject to investment			25.00%
Total mortgage loan receivables held for investment, net, at amortized cost \| Asset Specific Reserve, Company Loan
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loan reserve amount				$ 10,000,000.0
First mortgage loans
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loans receivable with fixed rates of interest		$ 174,000,000.0	$ 182,400,000		$ 174,000,000.0
Percentage of loans receivable with fixed rates of interest		100.00%	100.00%		100.00%
Loan on non-accrual status
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loans nonaccrual status, amount		$ 0	$ 0		$ 0