Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended
	Mar. 31, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Equity [Line Items]
Common shares issued during period	23,000,000
Proceeds from issuance of common shares				$ 306,986	$ 5,816
Proceeds from Issuance of Common Stock, Gross	258,336
Proceeds from Issuance of Common Stock, Net of Issuance Costs	293,855
OP Unit Equivalent in Common Shares				1.13
Partners Capital Account, Shares Issued For Units Redeemed				169,676	211,138
OP Units Outstanding		3,647,000		3,647,000
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax [Roll Forward]
Gains and Losses on Cash Flow Hedges, Beginning				(6,224)
Gains and Losses on Cash Flow Hedges, Ending		2,299		2,299
Transfers from noncontrolling interests:
Net income (loss) attributable to Lexington Realty Trust shareholders		4,695	174,541	8,807	182,663
Increase in additional paid-in-capital for redemption of noncontrolling OP units				887	1,099
Change from net income (loss) attributable to shareholders and transfers from noncontrolling interest				9,694	183,762
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax [Roll Forward]
Gains and Losses on Cash Flow Hedges, Beginning				(6,224)
Other comprehensive income before reclassifications				6,349
Amounts of loss reclassified from accumulated other comprehensive loss to interest expense				2,174
Gains and Losses on Cash Flow Hedges, Ending		2,299		2,299
Accumulated Distributions in Excess of Net Income [Member]
Transfers from noncontrolling interests:
Net income (loss) attributable to Lexington Realty Trust shareholders				8,807	182,663
Direct Share Purchase Plan [Member]
Equity [Line Items]
Common shares issued during period				1,052,159	777,882
Proceeds from issuance of common shares				11,600	6,079
At The Market [Member]
Equity [Line Items]
Common shares issued during period				3,409,927
Stockholders' Equity, Share Issuance Plan, Value Authorized				100,000
Stock Issued During Period, Value, New Issues				36,884
Officers [Member]
Equity [Line Items]
Deferred compensation arrangement with individual, shares issued				1,325,000
Deferred compensation arrangement with individual, fair value of shares issued				14,098
Trustees [Member]
Equity [Line Items]
Deferred compensation arrangement with individual, shares issued				37,500
Deferred compensation arrangement with individual, fair value of shares issued				$ 399