Income per Common Unit of the Operating Partnership (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net Income Available to Common Unitholders, Basic [Abstract]
Income from continuing operations net of noncontrolling interest																	$ 170,471	$ 91,274	$ 88,008
Excess of preferred unit redemption over carrying amount																		(1,236)
Excess of preferred unit carrying amount over redemption																			3,689
Discontinued operations	306		133		296		47,846		51,832		6,544		13,633		49,830		48,581	121,839	51,004
Net income available to common shareholders																	217,910	209,738	137,436
Weighted Average Number of Units Outstanding, Diluted [Abstract]
Weighted Average Number of Shares Outstanding, Basic																	147,216	130,180	116,863
Dilutive units for long-term compensation plans																	670	729	831
Weighted Average Number of Shares Outstanding, Diluted																	147,886	130,909	117,694
Earnings Per Share, Basic [Abstract]
Income per common share - basic	$ 0.56	[1]	$ 0.23	[1]	$ 0.20	[1]	$ 0.49	[1]	$ 0.48	[1]	$ 0.21	[1]	$ 0.33	[1]	$ 0.60	[1]
Earnings Per Share, Diluted [Abstract]
Income per common share - diluted	$ 0.55	[1]	$ 0.23	[1]	$ 0.20	[1]	$ 0.49	[1]	$ 0.48	[1]	$ 0.21	[1]	$ 0.33	[1]	$ 0.60	[1]
Liberty Property Limited Partnership [Member]
Net Income Available to Common Unitholders, Basic [Abstract]
Income from continuing operations net of noncontrolling interest																	175,035	97,102	97,022
Less: Preferred unit distributions																	(472)	(2,119)	(9,902)
Excess of preferred unit redemption over carrying amount																	0	(1,236)
Excess of preferred unit carrying amount over redemption																	0		3,689
Income from Continuing Operations available to Common Unitholders																	174,563	93,747	90,809
Discontinued operations																	48,581	121,839	51,004
Net income available to common shareholders																	$ 223,144	$ 215,586	$ 141,813
Weighted Average Number of Units Outstanding, Diluted [Abstract]
Weighted Average Number of Shares Outstanding, Basic																	150,770	133,858	120,623
Dilutive units for long-term compensation plans																	670	729	831
Weighted Average Number of Shares Outstanding, Diluted																	151,440	134,587	121,454
Liberty Property Limited Partnership [Member] | Common Units [Member]
Earnings Per Share, Basic [Abstract]
Income from Continuing Operations, Per Basic Share																	$ 1.16	$ 0.70	$ 0.75
Income from Discontinued Operations, Per Basic Share																	$ 0.32	$ 0.91	$ 0.43
Income per common share - basic																	$ 1.48	$ 1.61	$ 1.18
Earnings Per Share, Diluted [Abstract]
Income from Continuing Operations, Per Diluted Share																	$ 1.15	$ 0.70	$ 0.75
Income from Discontinued Operations, Per Diluted Share																	$ 0.32	$ 0.90	$ 0.42
Income per common share - diluted																	$ 1.47	$ 1.60	$ 1.17

[1] The sum of quarterly financial data may vary from the annual data due to rounding.