Income per Common Unit of the Operating Partnership (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Per Common Unit [Line Items]
Income from continuing operations net of noncontrolling interest																	$ 91,274	$ 88,008	$ 81,392
Excess of preferred unit carrying amount over redemption																	(1,236)
Preferred Stock Redemption Discount																		3,689
Weighted Average Number of Shares Outstanding, Basic																	130,180,000	116,863,000	114,755,000
Income from continuing operations net of noncontrolling interest, per common unit, basic																	$ 0.70	$ 0.75	$ 0.71
Dilutive units for long-term compensation plans																	729,000	831,000	748,000
Weighted Average Shares, Diluted																	130,909,000	117,694,000	115,503,000
Income from Continuing Operations, Per Diluted Common Unit																	$ 0.70	$ 0.75	$ 0.70
Discontinued operations	51,832		6,544		13,633		49,830		16,795		7,539		12,956		13,714		121,839	51,004	106,065
Discontinued operations net of noncontrolling interest, per common unit, basic																	$ 0.91	$ 0.43	$ 0.89
Discontinued operations net of noncontrolling interest, per common unit, diluted																	$ 0.90	$ 0.42	$ 0.89
Net Income Available to Common Shareholders, Basic																	209,738	137,436	183,999
Earnings Per Common Unit, Basic	$ 0.48	[1]	$ 0.21	[1]	$ 0.33	[1]	$ 0.60	[1]	$ 0.33	[1]	$ 0.24	[1]	$ 0.29	[1]	$ 0.32	[1]	$ 1.61	$ 1.18	$ 1.60
Earnings Per Common Unit, Diluted	$ 0.48	[1]	$ 0.21	[1]	$ 0.33	[1]	$ 0.60	[1]	$ 0.32	[1]	$ 0.24	[1]	$ 0.29	[1]	$ 0.32	[1]	$ 1.60	$ 1.17	$ 1.59
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount																	959,000	905,000	1,685,000
Stock Options Exercised																	504,000	841,000	256,000
Common Units Exchanged																	157,285	94,895	119,987
Common Stock, Dividends, Per Share, Declared																	$ 1.90	$ 1.90	$ 1.90
Liberty Property Limited Partnership [Member]
Income Per Common Unit [Line Items]
Income from continuing operations net of noncontrolling interest																	97,102	97,022	105,156
Noncontrolling Interest in Net Income (Loss) Preferred Unit Holders, Redeemable																	2,119	9,902	21,069
Excess of preferred unit carrying amount over redemption																	(1,236)
Preferred Stock Redemption Discount																		3,689	0
Income from Continuing Operations available to Common Unitholders																	93,747	90,809	84,087
Weighted Average Number of Shares Outstanding, Basic																	133,858,000	120,623,000	118,624,000
Income from continuing operations net of noncontrolling interest, per common unit, basic																	$ 0.70	$ 0.75	$ 0.71
Dilutive units for long-term compensation plans																	729,000	831,000	748,000
Weighted Average Shares, Diluted																	134,587,000	121,454,000	119,372,000
Income from Continuing Operations, Per Diluted Common Unit																	$ 0.70	$ 0.75	$ 0.70
Discontinued operations																	121,839	51,004	106,065
Discontinued operations net of noncontrolling interest, per common unit, basic																	$ 0.91	$ 0.43	$ 0.89
Discontinued operations net of noncontrolling interest, per common unit, diluted																	$ 0.90	$ 0.42	$ 0.89
Net Income Available to Common Shareholders, Basic																	215,586	141,813	190,152
Earnings Per Common Unit, Basic																	$ 1.61	$ 1.18	$ 1.60
Earnings Per Common Unit, Diluted																	$ 1.60	$ 1.17	$ 1.59
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount																	959,000	905,000	1,685,000
Stock Options Exercised																	504,000	841,000	256,000
Common Units Exchanged																		94,895	119,987
Common Stock, Dividends, Per Share, Declared																	$ 1.90	$ 1.90	$ 1.90
General Partners Equity [Member] | Liberty Property Limited Partnership [Member]
Income Per Common Unit [Line Items]
Excess of preferred unit carrying amount over redemption
Preferred Stock Redemption Discount
Common Units Exchanged																	157,285

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