Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended									12 Months Ended										24 Months Ended	12 Months Ended		12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Mar. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Accumulated Distributions in Excess of Net Income [Member]	Dec. 31, 2011 Accumulated Distributions in Excess of Net Income [Member]	Dec. 31, 2010 Accumulated Distributions in Excess of Net Income [Member]	Dec. 31, 2012 Series C	Dec. 31, 2012 Series C Minimum [Member]	Dec. 31, 2012 Series B	Dec. 31, 2011 Series B	Dec. 31, 2012 Series B	Dec. 31, 2012 Six Percent Convertible Guaranteed Note [Member]	Mar. 31, 2010 Six Percent Convertible Guaranteed Note [Member]	Dec. 31, 2012 Public Offering And Direct Share Purchase Plan Proceeds [Member]	Dec. 31, 2011 Public Offering And Direct Share Purchase Plan Proceeds [Member]	Dec. 31, 2010 Public Offering And Direct Share Purchase Plan Proceeds [Member]	Dec. 31, 2012 Cumulative Convertible Series C	Dec. 31, 2011 Cumulative Convertible Series C
Equity [Line Items]
Common shares issued	178,616,664				154,938,351					178,616,664	154,938,351
Common shares issued through public offering and direct share purchase plan during period										18,289,557	11,109,760	23,712,980
Proceeds from issuance of common shares										$ 162,747	$ 99,730	$ 166,652											$ 164,429	$ 98,953	$ 166,427
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt									13,134
Debt interest rate percentage																						6.00%
Unrealized gain (loss) on interest rate swap in Accumulated Other Comprehensive Income	(6,224)				1,938					(6,224)	1,938
Preferred Stock, Shares Outstanding																										1,935,400	1,970,200
Preferred Stock, Dividend Rate, Per-Dollar-Amount																$ 3.25
Preferred Stock Aggregate Liquidation Preference Value																										96,770	98,510
Preferred Shares to Common Shares Conversion Ratio																2.4339
Common Share Closing Price Percent of Conversion Price																	125.00%
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures										643,450	609,182	361,320
OP Unit Equivalent in Common Shares										1.13
OP Units Outstanding	3,797,000									3,797,000
Partners Capital Account, Shares Issued For Units Redeemed										257,427	398,927	457,351
Transfers from noncontrolling interests:
Net income (loss) attributable to Lexington Realty Trust shareholders	(1,755)	175,289	5,626	5,478	14,016	(30,844)	(56,957)	(15,993)		184,638	(89,778)	(37,410)	180,316	(79,584)	(32,960)
Increase in additional paid-in-capital for redemption of noncontrolling OP units										1,343	2,187	2,685
Change from net income (loss) attributable to shareholders and transfers from noncontrolling interests										181,659	(77,397)	(30,275)
Adjustments to Additional Paid in Capital, Equity Component of Convertible Debt, Subsequent Adjustments										3,654
Stock Issued During Period, Shares, Conversion of Convertible Securities										4,487,060
Debt Conversion, Converted Instrument, Amount																					31,104
Repurchase Of Preferred Shares																				3,160,000
Payments for Repurchase of Preferred Stock and Preference Stock										$ 70,000	$ 15,456	$ 0						$ 68,539	$ 10,217