Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Equity [Line Items]
Common shares issued during period			777,882	733,673
Proceeds from issuance of common shares			$ 5,772	$ 96,595
Unrealized gain (loss) on interest rate swap in Accumulated Other Comprehensive Income	(6,393)		(6,393)		1,938
OP Unit Equivalent in Common Shares			1.13
Partners Capital Account, Shares Issued For Units Redeemed			211,138	340,550
OP Units Outstanding	3,839,000		3,839,000
Transfers from noncontrolling interests:
Net income (loss) attributable to Lexington Realty Trust shareholders	174,541	(30,914)	182,663	(92,611)
Increase in additional paid-in-capital for redemption of noncontrolling OP units			1,099	1,876
Change from net income (loss) attributable to shareholders and transfers from noncontrolling interest			183,762	(90,735)
Accumulated Distributions in Excess of Net Income [Member]
Transfers from noncontrolling interests:
Net income (loss) attributable to Lexington Realty Trust shareholders			182,663	(92,611)
Direct Share Purchase Plan [Member]
Equity [Line Items]
Proceeds from issuance of common shares			6,079	6,090
Public Offering [Member]
Equity [Line Items]
Common shares issued during period				10,000,000
Stock Issued During Period, Value, New Issues				$ 90,505