Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

+ Details

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

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ 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(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=lxp_UnsecuredTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=lxp_UnsecuredRevolvingCreditFacilityExpiringAugust2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=lxp_UnsecuredTermLoanExpiringAugust2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=lxp_UnsecuredTermLoanExpiringFebruary2018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=lxp_UnsecuredTermLoanExpiringJanuary2021Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=lxp_UnsecuredTermLoanExpiringJanuary2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=lxp_LCIFMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=lxp_UnsecuredRevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Mortgages and Notes Payable - Credit Agreement Terms (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Aug. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Revolving credit facility borrowings		$ 160,000,000		$ 0
Remaining borrowing capacity		345,000,000
Debt issuance costs, net		7,258,000
Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Debt issuance costs, gross		3,337,000		$ 3,907,000
Unsecured Revolving Credit Facility, Expiring August 2019 [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Face amount		505,000,000	$ 400,000,000
Revolving credit facility borrowings		$ 160,000,000
Unsecured Term Loan, Expiring August 2020 [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		0.90%
Unsecured Term Loan, Expiring August 2020 [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		1.75%
Unsecured Term Loan, Expiring August 2020 [Member] \| Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Face amount		$ 300,000,000	250,000,000
Unsecured Term Loan, Expiring February 2018 [Member] \| Interest Rate Swap [Member]
Debt Instrument [Line Items]
Weighted-average interest rate		1.09%
Unsecured Term Loan, Expiring February 2018 [Member] \| Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Face amount		$ 250,000,000
Unsecured Term Loan, Expiring January 2021 [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		0.90%
Unsecured Term Loan, Expiring January 2021 [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		1.75%
Unsecured Term Loan, Expiring January 2021 [Member] \| Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Face amount		$ 300,000,000	255,000,000
Unsecured Term Loan, Expiring January 2019 [Member] \| Interest Rate Swap [Member]
Debt Instrument [Line Items]
Weighted-average interest rate		1.42%
Unsecured Term Loan, Expiring January 2019 [Member] \| Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Face amount		$ 255,000,000
London Interbank Offered Rate (LIBOR) [Member] \| Unsecured Revolving Credit Facility, Expiring August 2019 [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		0.85%
London Interbank Offered Rate (LIBOR) [Member] \| Unsecured Revolving Credit Facility, Expiring August 2019 [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		1.55%
London Interbank Offered Rate (LIBOR) [Member] \| Unsecured Revolving Credit Facility, Expiring August 2019 [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		1.00%
London Interbank Offered Rate (LIBOR) [Member] \| Unsecured Term Loan, Expiring August 2020 [Member] \| Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		1.10%
London Interbank Offered Rate (LIBOR) [Member] \| Unsecured Term Loan, Expiring January 2021 [Member] \| Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		1.10%
LCIF [Member]
Debt Instrument [Line Items]
Remaining borrowing capacity		$ 345,000,000
Weighted-average interest rate		4.80%		4.70%
Debt issuance costs, net		$ 1,511,000
LCIF [Member] \| Unsecured Revolving Credit Facility, Expiring August 2019 [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR	0.85%
LCIF [Member] \| Unsecured Revolving Credit Facility, Expiring August 2019 [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR	1.55%
LCIF [Member] \| Unsecured Revolving Credit Facility, Expiring August 2019 [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Face amount		505,000,000	400,000,000
LCIF [Member] \| Unsecured Revolving Credit Facility, Expiring August 2019 [Member] \| Unsecured Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Revolving credit facility borrowings		$ 160,000,000
LCIF [Member] \| Unsecured Term Loan, Expiring August 2020 [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		0.90%
LCIF [Member] \| Unsecured Term Loan, Expiring August 2020 [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		1.75%
LCIF [Member] \| Unsecured Term Loan, Expiring August 2020 [Member] \| Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Face amount		$ 300,000,000	250,000,000
LCIF [Member] \| Unsecured Term Loan, Expiring February 2018 [Member] \| Interest Rate Swap [Member]
Debt Instrument [Line Items]
Weighted-average interest rate		1.09%
LCIF [Member] \| Unsecured Term Loan, Expiring February 2018 [Member] \| Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Face amount		$ 250,000,000
LCIF [Member] \| Unsecured Term Loan, Expiring January 2021 [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		0.90%
LCIF [Member] \| Unsecured Term Loan, Expiring January 2021 [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		1.75%
LCIF [Member] \| Unsecured Term Loan, Expiring January 2021 [Member] \| Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Face amount		$ 300,000,000	$ 255,000,000
LCIF [Member] \| Unsecured Term Loan, Expiring January 2019 [Member] \| Interest Rate Swap [Member]
Debt Instrument [Line Items]
Weighted-average interest rate		1.42%
LCIF [Member] \| Unsecured Term Loan, Expiring January 2019 [Member] \| Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Face amount		$ 255,000,000
LCIF [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Unsecured Revolving Credit Facility, Expiring August 2019 [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		1.00%
LCIF [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Unsecured Term Loan, Expiring August 2020 [Member] \| Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		1.10%
LCIF [Member] \| London Interbank Offered Rate (LIBOR) [Member] \| Unsecured Term Loan, Expiring January 2021 [Member] \| Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Interest rate stated percentage rate range minimum excluding LIBOR		1.10%