Investments in Real Estate and Real Estate Under Construction Acquisition, Pro Forma (Details) (Net Lease Strategic Assets Fund L P [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Net Lease Strategic Assets Fund L P [Member]
Business Acquisition [Line Items]
Gross revenues	$ 92,795	$ 181,650
Net income (loss) attributable to Lexington Realty Trust shareholders	7	(4,837)
Net loss attributable to common shareholders	$ (7,896)	$ (18,538)
Net loss per common share - basic and diluted	$ (0.05)	$ (0.12)