Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Equity [Line Items]
Proceeds from issuance of common shares	$ 297,823	$ 2,145
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax [Roll Forward]
Unrealized gain (loss) on interest rate swap in Accumulated Other Comprehensive Income	(6,224)
Unrealized gain (loss) on interest rate swap in Accumulated Other Comprehensive Income	(5,522)
OP Unit Equivalent in Common Shares	1.13
Partners Capital Account, Shares Issued For Units Redeemed	88,442
OP Units Outstanding	3,719,000
Transfers from noncontrolling interests:
Net income (loss) attributable to Lexington Realty Trust shareholders	(2,620)	3,611
Increase in additional paid-in-capital for redemption of noncontrolling OP units	458	0
Change from net income (loss) attributable to shareholders and transfers from noncontrolling interest	(2,162)	3,611
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]
Unrealized gain (loss) on interest rate swap in Accumulated Other Comprehensive Income	(6,224)
Other comprehensive income before reclassifications	262
Amounts of loss reclassified from accumulated other comprehensive loss to interest expense	440
Unrealized gain (loss) on interest rate swap in Accumulated Other Comprehensive Income	(5,522)
Accumulated Distributions in Excess of Net Income [Member]
Transfers from noncontrolling interests:
Net income (loss) attributable to Lexington Realty Trust shareholders	(2,620)	3,611
Direct Share Purchase Plan [Member]
Equity [Line Items]
Common shares issued during period	316,759	298,662
Proceeds from issuance of common shares	3,212	2,145
Public Offering [Member]
Equity [Line Items]
Common shares issued during period	23,000,000
Stock Issued During Period, Value, New Issues	258,086
At The Market [Member]
Equity [Line Items]
Common shares issued during period	3,409,927
Stock Issued During Period, Value, New Issues	35,925
Stockholders' Equity, Share Issuance Plan, Value Authorized	100,000
Officers [Member]
Transfers from noncontrolling interests:
Deferred compensation arrangement with individual, shares issued	1,325,000
Deferred compensation arrangement with individual, fair value of shares issued	14,098
Trustees [Member]
Transfers from noncontrolling interests:
Deferred compensation arrangement with individual, shares issued	37,500
Deferred compensation arrangement with individual, fair value of shares issued	$ 399