Investments in Real Estate and Real Estate Under Construction (Details) (USD $)	3 Months Ended																12 Months Ended						12 Months Ended																																									0 Months Ended	12 Months Ended
	Dec. 31, 2013 properties states		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012 properties states		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013 properties states		Dec. 31, 2012 properties states		Dec. 31, 2011	Dec. 31, 2013 Lender Subsidiary [Member] sqft	Dec. 31, 2013 Office Property [Member] Denver, Colorado [Member]		Dec. 31, 2013 Office Property [Member] Other Locations [Member] properties		Dec. 31, 2013 Office Property [Member] Omaha, Nebraska [Member]	Dec. 31, 2012 Office Property [Member] Huntington, West Virginia [Member]	Dec. 31, 2012 Office Property [Member] Florence, South Carolina [Member]	Dec. 31, 2012 Office Property [Member] Jessup, Pennsylvania [Member]	Dec. 31, 2012 Office Property [Member] Saint Joseph, Missouri [Member]	Dec. 31, 2012 Office Property [Member] Phoenix, Arizona [Member]	Dec. 31, 2012 Office Property [Member] Eugene, Oregon [Member]	Dec. 31, 2013 Office Property [Member] Las Vegas, Nevada [Member] sqft	Dec. 31, 2013 Industrial Property [Member] Long Island City, New York [Member]	Dec. 31, 2013 Industrial Property [Member] Houston, Texas [Member]	Dec. 31, 2012 Industrial Property [Member] Missouri City, Texas [Member]	Dec. 31, 2012 Industrial Property [Member] Shreveport, Louisiana [Member]	Dec. 31, 2013 Industrial Property [Member] Rantoul, Illinois [Member] sqft	Dec. 31, 2013 Industrial Property [Member] Bingen, Washington [Member] sqft	Dec. 31, 2013 Industrial Property [Member] Lewisburg, Tennessee [Member]	Dec. 31, 2013 Retail Property [Member] Tuscaloosa, Alabama [Member]		Dec. 31, 2013 Retail Property [Member] Albany, Georgia [Member]		Dec. 31, 2013 Retail Property [Member] Valdosta, Georgia [Member]	Dec. 31, 2012 Retail Property [Member] Valdosta, Georgia [Member]		Dec. 31, 2013 Retail Property [Member] Opelika Alabama [Member]	Dec. 31, 2012 Retail Property [Member] Opelika Alabama [Member]		Dec. 31, 2013 Retail Property [Member] Richmond, Virginia [Member] sqft	Dec. 31, 2013 Land [Member] New York, New York [Member] properties		Dec. 31, 2013 Land [Member] Danville, Virginia [Member]	Dec. 31, 2013 Development Deals [Member]	Dec. 31, 2012 Development Deals [Member]	Dec. 31, 2013 In-place Lease Values [Member]	Dec. 31, 2012 In-place Lease Values [Member]	Dec. 31, 2013 Tenant Relationship Values [Member]	Dec. 31, 2012 Tenant Relationship Values [Member]	Dec. 31, 2013 Above-market Leases [Member]	Dec. 31, 2012 Above-market Leases [Member]	Sep. 01, 2012 Net Lease Strategic Assets Fund L P [Member] states properties sqft	Dec. 31, 2013 Net Lease Strategic Assets Fund L P [Member]	Dec. 31, 2012 Net Lease Strategic Assets Fund L P [Member]	Dec. 31, 2011 Net Lease Strategic Assets Fund L P [Member]	Dec. 31, 2013 Net Lease Strategic Assets Fund L P [Member] In-place Lease Values [Member]	Dec. 31, 2013 Net Lease Strategic Assets Fund L P [Member] Tenant Relationship Values [Member]	Dec. 31, 2013 Net Lease Strategic Assets Fund L P [Member] Above-market Leases [Member]	Sep. 01, 2012 Common Stock [Member] Net Lease Strategic Assets Fund L P [Member]	Sep. 01, 2012 Preferred Shares [Member] Net Lease Strategic Assets Fund L P [Member]
Investments in Real Estate and Real Estate Under Construction [Line Items]
Real Estate Revenue, Net	$ 109,606,000	[1]	$ 96,950,000	[1]	$ 97,763,000	[1]	$ 94,121,000	[1]	$ 92,059,000	[1]	$ 83,800,000	[1]	$ 78,961,000	[1]	$ 75,360,000	[1]	$ 398,440,000		$ 330,180,000		$ 292,298,000																																												$ 42,576,000	$ 14,504,000
Net loss attributable to Lexington Realty Trust shareholders	(7,001,000)		5,155,000		7,832,000		(2,123,000)		(1,755,000)		175,289,000		5,626,000		5,478,000		3,863,000		184,638,000		(89,778,000)																																												4,419,000	1,667,000
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain																																																																167,864,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncontrolling Interest																																																																373,000
Gain (Loss) on Acquisition of Real Estate																	0		167,864,000		0																																													167,864,000
Real Estate and Accumulated Depreciation and Amortization
Buildings and building improvements	3,008,709,000								2,969,050,000								3,008,709,000		2,969,050,000
Land, land estates and land improvements	793,418,000								581,199,000								793,418,000		581,199,000
Fixtures and equipment	5,861,000								7,705,000								5,861,000		7,705,000
Construction in progress	4,306,000								6,512,000								4,306,000		6,512,000						1,969,000
Real estate intangibles:	762,157,000								685,914,000								762,157,000		685,914,000																																							486,743,000	401,503,000	172,640,000	179,655,000	102,774,000	104,756,000
Investments in real estate under construction	74,350,000								65,122,000								74,350,000		65,122,000
Real estate, gross	4,648,801,000								4,315,502,000								4,648,801,000		4,315,502,000
Accumulated depreciation and amortization	(1,223,381,000)	[2]							(1,150,417,000)	[2]							(1,223,381,000)	[2]	(1,150,417,000)	[2]
Real estate, net	3,425,420,000								3,165,085,000								3,425,420,000		3,165,085,000
Finite-Lived Intangible Assets, Accumulated Amortization	447,764,000								412,349,000								447,764,000		412,349,000
Estimated Amortization, 2014	44,003,000																44,003,000
Estimated Amortization, 2015	34,932,000																34,932,000
Estimated Amortization, 2016	28,640,000																28,640,000
Estimated Amortization, 2017	25,239,000																25,239,000
Estimated Amortization, 2018	21,498,000																21,498,000
Below Market Leases [Abstract]
Below-market Leases, Net of Accretion	59,781,000								71,513,000								59,781,000		71,513,000
Future Accretion, 2014																	5,176,000
Future Accretion, 2015																	4,489,000
Future Accretion, 2016																	3,380,000
Future Accretion, 2017																	2,935,000
Future Accretion, 2018																	2,911,000
Acquired Properties [Abstract]
Initial Cost Basis																	532,538,000		182,608,000				34,547,000	[3]	13,144,000	[4]	39,125,000	12,558,000	5,094,000	24,917,000	17,571,000	53,200,000	17,558,000		42,124,000	81,400,000	23,000,000	12,941,000				8,397,000	[5]	7,074,000	[6]		7,791,000	[7]		7,978,000	[7]		302,000,000	[8]	4,727,000
Land	253,492,000								31,602,000								253,492,000		31,602,000				2,207,000	[3]	1,522,000	[4]	2,058,000	1,368,000	774,000	2,520,000	607,000	5,585,000	1,541,000		0	15,055,000	14,555,000	1,078,000				2,793,000	[5]	1,468,000	[6]		2,128,000	[7]		1,446,000	[7]		224,935,000	[8]	3,454,000
Buildings and building improvements	180,724,000								122,238,000								180,724,000		122,238,000				26,724,000	[3]	10,374,000	[4]	32,343,000	9,527,000	3,629,000	17,656,000	14,004,000	36,099,000	13,099,000		42,124,000	57,949,000	5,895,000	10,134,000				5,604,000	[5]	5,606,000	[6]		5,663,000	[7]		6,532,000	[7]		0	[8]	0
Finite-Lived Intangible Asset, Off-market Lease, Favorable, Gross	673,000																673,000						0	[3]	0	[4]	0								0	0						0	[5]	0	[6]								0	[8]	673,000
Lease in-place Value	97,649,000								22,869,000								97,649,000		22,869,000				5,616,000	[3]	1,248,000	[4]	4,724,000	1,405,000	505,000	3,336,000	2,528,000	8,956,000	2,414,000		0	8,396,000	2,135,000	1,590,000				0	[5]	0	[6]		0	[7]		0	[7]		77,065,000	[8]	600,000
Customer Relationships Value									5,899,000										5,899,000									258,000	186,000	1,405,000	432,000	2,560,000	504,000				415,000	139,000									0	[7]		0	[7]
Weighted-average life of intangible assets (years)																																																										15 years 3 months 18 days	15 years 8 months 12 days	82 years 6 months	16 years							6 years 2 months 12 days	4 years 7 months 6 days	8 years 4 months 24 days
Incurred tenant costs																							3,825,000
Incurred leasing costs																																										323,000		338,000		488,000			355,000
Deposit Towards Purchase Of Property																																									638,000
Estimated Property Purchase Price/Completion Cost																																									12,767,000
Acquisition expenses																	812,000		947,000																																															230,000
Development Arrangements Outstanding [Abstract]
Square feet																						1,396,000												180,000					813,000	124,000												279,000												5,800,000
Expected Maximum Commitment/Contribution																						189,700,000												29,600,000					42,600,000	18,900,000												98,600,000
Lease term																																		20 years					20 years	12 years												15 years
Real Estate Investment Capitalized Interest																																																								1,472,000	1,291,000
Business Acquisition, Cost of Acquired Entity, Cash Paid																																																																9,438,000
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage																																																																							15.00%	100.00%
Real Estate Investments, Joint Ventures																																																																40,047,000
Number of Consolidated Properties	220								220								220		220						4																												3											41
Number of States in which Entity Operates	41								41								41		41																																													23
Tenant in Common Interest, Ownership Percentage																																																																40.00%
Business Combination, Major Class of Assets and Liabilities
Real estate assets																																																																325,310,000
Lease related intangible assets																																																																124,330,000
Cash																																																																8,107,000
Other assets																																																																36,179,000
Total acquired assets																																																																493,926,000
Secured debt																																																																252,517,000
Other liabilities, including below-market leases																																																																23,686,000
Total assumed liabilities																																																																276,203,000
Fair value of acquired net assets (represents 100% interest)																																																																217,723,000
Acquired Finite-lived Intangible Asset, Amount																																																																	124,330,000			59,819,000	24,828,000	39,683,000
Off-market Lease, Unfavorable	69,667,000								79,908,000								69,667,000		79,908,000																																														1,529,000
Acquired Finite-lived Intangible Liability, Weighted Average Useful Life																																																																	2 years 8 months 12 days
Weighted-average life of intangible assets																																																										15 years 3 months 18 days	15 years 8 months 12 days	82 years 6 months	16 years							6 years 2 months 12 days	4 years 7 months 6 days	8 years 4 months 24 days
Gross revenues																																																																		372,603,000	356,918,000
Net income (loss) attributable to Lexington Realty Trust shareholders																																																																		8,000	(111,787,000)
Net loss attributable to common shareholders																																																																		$ (22,985,000)	$ (135,924,000)
Net loss per common share - basic and diluted																																																																		$ (0.14)	$ (0.89)

[1] All periods have been adjusted to reflect the impact of properties sold during the years ended December 31, 2013 and 2012, and properties classified as held for sale, which are reflected in discontinued operations in the Consolidated Statements of Operations.

[2] Includes accumulated amortization of real estate intangible assets of $447,764 and $412,349 in 2013 and 2012, respectively. The estimated amortization of the above real estate intangible assets for the next five years is $44,003 in 2014, $34,932 in 2015, $28,640 in 2016, $25,239 in 2017 and $21,498 in 2018.

[3] The Company incurred additional tenant related costs of $3,825.

[4] Includes four properties. One property was under construction at December 31, 2013, $1,969 of construction in progress costs are included in building and improvements above.

[5] The Company incurred leasing costs of $323. The property was sold in September 2013.

[6] The Company incurred leasing costs of $338.

[7] Incurred leasing costs of $488 for Valdosta and $355 for Opelika. Properties were sold in 2013.

[8] Includes three properties.