Investments in Real Estate and Real Estate Under Construction (Details) (USD $)	3 Months Ended													12 Months Ended						12 Months Ended													12 Months Ended						12 Months Ended											0 Months Ended	12 Months Ended				12 Months Ended			12 Months Ended		12 Months Ended
	Dec. 31, 2012 states properties		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011 properties states		Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 states properties		Dec. 31, 2011 properties states		Dec. 31, 2010	Dec. 31, 2012 Corporate Joint Venture [Member]	Dec. 31, 2012 Lender Subsidiary [Member] sqft	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, 2011 Office Property [Member] Rock Hill, South Carolina [Member]	Dec. 31, 2011 Office Property [Member] Allen, Texas [Member]		Dec. 31, 2011 Office Property [Member] Columbus, Ohio [Member]	Dec. 31, 2011 Office Property [Member] Aurora, Illinois [Member]		Dec. 31, 2012 Office Property [Member] Denver Colorado [Member] sqft Y	Dec. 31, 2012 Industrial Property [Member] Missouri City Texas [Member]	Dec. 31, 2012 Industrial Property [Member] Shreveport, Louisiana [Member]	Dec. 31, 2011 Industrial Property [Member] Byhalia, Mississippi [Member]	Dec. 31, 2011 Industrial Property [Member] Shelby, North Carolina [Member]	Dec. 31, 2011 Industrial Property [Member] Chillicothe Ohio [Member]	Dec. 31, 2012 Industrial Property [Member] Long Island City, New York [Member] Y sqft		Dec. 31, 2012 Industrial Property [Member] Rantoul Illinois [Member] sqft Y	Dec. 31, 2012 Retail Property [Member] Valdosta Georgia [Member]		Dec. 31, 2012 Retail Property [Member] Opelika Alabama [Member]		Dec. 31, 2012 Retail Property [Member] Tuscaloosa Alabama [Member] sqft Y	Dec. 31, 2012 Development Deals [Member]	Dec. 31, 2011 Development Deals [Member]	Dec. 31, 2012 Payment Guarantee [Member]	Sep. 01, 2012 Net Lease Strategic Assets Fund L P [Member] sqft states properties	Dec. 31, 2012 Net Lease Strategic Assets Fund L P [Member] Y	Dec. 31, 2011 Net Lease Strategic Assets Fund L P [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]	Dec. 31, 2008 Scenario, Previously Reported [Member] Net Lease Strategic Assets Fund L P [Member]	Dec. 31, 2007 Scenario, Previously Reported [Member] Net Lease Strategic Assets Fund L P [Member]	Dec. 31, 2012 Restatement Adjustment [Member] Net Lease Strategic Assets Fund L P [Member]	Dec. 31, 2011 Above Market Leases [Member] Y	Dec. 31, 2012 Above Market Leases [Member]	Dec. 31, 2012 Above Market Leases [Member] Net Lease Strategic Assets Fund L P [Member] Y	Dec. 31, 2012 Tenant Relationships [Member] years	Dec. 31, 2011 Tenant Relationships [Member] Y	Dec. 31, 2012 Tenant Relationships [Member] Net Lease Strategic Assets Fund L P [Member] Y	Dec. 31, 2012 Leases, Acquired-in-Place [Member] years	Dec. 31, 2011 Leases, Acquired-in-Place [Member] Y	Dec. 31, 2012 Leases, Acquired-in-Place [Member] Net Lease Strategic Assets Fund L P [Member] Y
Investments in Real Estate and Real Estate Under Construction [Line Items]
Finite-Lived Intangible Assets, Accumulated Amortization	$ 412,349								$ 368,349					$ 412,349		$ 368,349
Real Estate and Accumulated Depreciation and Amortization
Buildings and building improvements	2,969,050,000								2,638,626,000					2,969,050,000		2,638,626,000
Land, land estates and land improvements	581,199,000								522,039,000					581,199,000		522,039,000
Fixtures and equipment	7,705,000								7,525,000					7,705,000		7,525,000
Construction in progress	6,512,000								4,056,000					6,512,000		4,056,000
Real estate intangibles:	685,914,000								546,918,000					685,914,000		546,918,000																																										66,939,000	104,756,000		179,655,000	152,390,000		401,503,000	327,589,000
Investments in real estate under construction	65,122,000								34,529,000					65,122,000		34,529,000
Real estate, gross	4,315,502,000								3,753,693,000					4,315,502,000		3,753,693,000
Accumulated depreciation and amortization	(1,150,417,000)	[1]							(1,006,717,000)	[1]				(1,150,417,000)	[1]	(1,006,717,000)	[1]
Real estate, net	3,165,085,000								2,746,976,000					3,165,085,000		2,746,976,000
Intangible Assets [Abstract]
Estimated Amortization, 2013														58,797,000
Estimated Amortization, 2014														42,539,000
Estimated Amortization, 2015														32,799,000
Estimated Amortization, 2016														26,457,000
Estimated Amortization, 2017														23,056,000
Below Market Leases [Abstract]
Below-market Leases, Net of Accretion	71,513,000								78,806,000					71,513,000		78,806,000
Future Accretion, 2013														7,378,000
Future Accretion, 2014														5,901,000
Future Accretion, 2015														4,838,000
Future Accretion, 2016														3,729,000
Future Accretion, 2017														3,285,000
Acquired Properties [Abstract]
Initial Cost Basis	182,608,000								128,208,000					182,608,000		128,208,000					12,558,000	5,094,000	24,917,000	17,571,000	53,200,000	17,558,000	7,395,000	36,304,000	[2]	6,137,000	15,300,000	[3]		23,000,000	12,941,000	27,492,000	23,470,000	12,110,000				7,791,000	[4]	7,978,000	[4]
Land	31,602,000								12,800,000					31,602,000		12,800,000					1,368,000	774,000	2,520,000	607,000	5,585,000	1,541,000	551,000	5,591,000	[2]	433,000	3,063,000	[3]		14,555,000	1,078,000	1,005,000	1,421,000	736,000				2,128,000	[4]	1,446,000	[4]
Buildings and building improvements	122,238,000								84,057,000					122,238,000		84,057,000					9,527,000	3,629,000	17,656,000	14,004,000	36,099,000	13,099,000	4,313,000	21,607,000	[2]	2,773,000	5,943,000	[3]		5,895,000	10,134,000	21,483,000	18,917,000	9,021,000				5,663,000	[4]	6,532,000	[4]
Finite-Lived Intangible Asset, Off-market Lease, Favorable, Gross									1,272,000							1,272,000											0	0	[2]	0	1,272,000	[3]				0	0	0
Lease in-place Value	22,869,000								21,469,000					22,869,000		21,469,000					1,405,000	505,000	3,336,000	2,528,000	8,956,000	2,414,000	1,853,000	5,127,000	[2]	2,205,000	3,616,000	[3]		2,135,000	1,590,000	4,097,000	2,712,000	1,859,000				0	[4]	0	[4]
Customer Relationships Value	5,899,000								8,610,000					5,899,000		8,610,000					258,000	186,000	1,405,000	432,000	2,560,000	504,000	678,000	3,979,000	[2]	726,000	1,406,000	[3]		415,000	139,000	907,000	420,000	494,000				0	[4]	0	[4]
Weighted-average life of intangible assets (years)																																																										6.0		8.4	16.0	9.7	4.6	15.7	11.8	6.2
Incurred leasing costs																																										488,000		355,000
Acquisition expenses														947,000		386,000																																			230,000
Development Arrangements Outstanding [Abstract]
Square feet																				1,161,000													163,000						143,000	[5]	813,000					42,000				5,800,000
Expected Maximum Commitment/Contribution																				136,500,000													38,400,000						46,700,000	[5]	42,600,000					8,800,000
Estimated Property Purchase Price/Completion Cost																				145,300,000													38,400,000						55,500,000	[5]	42,600,000					8,800,000
Lease term																																	15						15	[5]	20					15
Guarantor Obligations, Current Carrying Value																																																	1,500,000
Maximum Loan to Joint Venture																			4,398,000
Real Estate Investment Capitalized Interest																																															1,291,000	619,000
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								185					220		185																																		41
Number of States in which Entity Operates	41								39					41		39																																		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
Gain on acquisition														167,864,000		0		0																																167,864,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncontrolling Interest																																																		373,000
Gain (Loss) on Acquisition of Real Estate														167,864,000		0		0																																	167,864,000				31,806,000	19,422,000
Acquired Finite-lived Intangible Asset, Amount																																																			124,330,000									39,683,000			24,828,000			59,819,000
Off-market Lease, Unfavorable	79,908,000								90,349,000					79,908,000		90,349,000																																			1,529,000
Weighted-average life of intangible assets																																																										6.0		8.4	16.0	9.7	4.6	15.7	11.8	6.2
Acquired Finite-lived Intangible Liability, Weighted Average Useful Life																																																			2.7
Real Estate Revenue, Net	95,533,000	[6]	87,473,000	[6]	82,750,000	[6]	79,123,000	[6]	79,570,000		79,492,000	77,474,000	77,290,000	344,879,000		313,826,000		305,350,000																																14,504,000
Net income (loss) attributable to Lexington Realty Trust shareholders	(1,755,000)		175,289,000		5,626,000		5,478,000		14,016,000		(30,844,000)	(56,957,000)	(15,993,000)	184,638,000		(89,778,000)		(37,410,000)																																1,667,000
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)
Accumulated Distributions in Excess of Net Income	$ 1,143,803,000								$ 1,212,630,000					$ 1,143,803,000		$ 1,212,630,000																																									$ 51,228,000

[1] Includes accumulated amortization of real estate intangible assets of $412,349 and $368,349 in 2012 and 2011, respectively. The estimated amortization of the above real estate intangible assets for the next five years is $58,797 in 2013, $42,539 in 2014, $32,799 in 2015, $26,457 in 2016 and $23,056 in 2017.

[2] The Company acquired the property from Net Lease Strategic Assets Fund L.P. pursuant to a purchase option.

[3] Obtained control of joint venture investment (see note 9).

[4] Incurred leasing costs of $488 for Valdosta and $355 for Opelika.

[5] Joint venture investment. The Company has guaranteed completion to the ground owner. The guarantee obligation was valued at $1,500 and is included in accounts payable and other liabilities in the Consolidated Balance Sheet. In addition, the Company may loan a maximum of $4,398 to the joint venture under certain circumstances. The difference between the Company's expected contribution and the estimated completion cost represents the joint venture partner's equity.

[6] All periods have been adjusted to reflect the impact of properties sold during the years ended December 31, 2012 and 2011, and properties classified as held for sale, which are reflected in discontinued operations in the Consolidated Statements of Operations.