Income per Common Unit of the Operating Partnership (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Income Per Common Unit [Line Items]
Income from continuing operations	$ 29,014	$ 26,848	$ 54,262	$ 49,751
Weighted Average Number of Shares Outstanding, Basic	147,012,000	120,081,000	146,749,000	119,416,000
Income from Continuing Operations, Per Basic Share	$ 0.20	$ 0.22	$ 0.37	$ 0.42
Dilutive units for long-term compensation plans	762,000	830,000	695,000	813,000
Weighted Average Number of Shares Outstanding, Diluted	147,774,000	120,911,000	147,444,000	120,229,000
Income from Continuing Operations, Per Diluted Share	$ 0.20	$ 0.22	$ 0.37	$ 0.42
Income from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	241	13,666	48,015	63,489
Income from Discontinued Operations, Net of Tax, Per Basic Share	$ 0.00	$ 0.11	$ 0.32	$ 0.51
Income from discontinued operations	$ 0.00	$ 0.11	$ 0.32	$ 0.51
Income available to common unitholders	29,249	40,109	101,149	111,348
Earnings Per Share, Basic	$ 0.20	$ 0.33	$ 0.69	$ 0.93
Earnings Per Share, Diluted	$ 0.20	$ 0.33	$ 0.69	$ 0.93
Dilutive Shares, Shares Issued, Shares Acquired on Exchange [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	750,000	625,000	750,000	773,000
Stock Issued During Period, Shares, Stock Options Exercised	42,000		43,000		504,000
Liberty Property Limited Partnership [Member]
Income Per Common Unit [Line Items]
Income from continuing operations	29,829	29,577	55,808	54,410
Less: Preferred unit distributions	(118)	(672)	(236)	(1,883)
Excess of preferred unit redemption over carrying amount	0	(1,236)	0	(1,236)
Income from Continuing Operations available to Common Unitholders	29,711	27,669	55,572	51,291
Weighted Average Number of Shares Outstanding, Basic	150,563,000	123,795,000	150,304,000	123,130,000
Income from Continuing Operations, Per Basic Share	$ 0.20	$ 0.22	$ 0.37	$ 0.42
Dilutive units for long-term compensation plans	762,000	830,000	695,000	813,000
Weighted Average Number of Shares Outstanding, Diluted	151,325,000	124,625,000	150,999,000	123,943,000
Income from Continuing Operations, Per Diluted Share	$ 0.20	$ 0.22	$ 0.37	$ 0.42
Income from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	241	13,666	48,015	63,489
Income from Discontinued Operations, Net of Tax, Per Basic Share	$ 0.00	$ 0.11	$ 0.32	$ 0.51
Income from discontinued operations	$ 0.00	$ 0.11	$ 0.32	$ 0.51
Income available to common unitholders	$ 29,952	$ 41,335	$ 103,587	$ 114,780
Earnings Per Share, Basic	$ 0.20	$ 0.33	$ 0.69	$ 0.93
Earnings Per Share, Diluted	$ 0.20	$ 0.33	$ 0.69	$ 0.93
Dilutive Shares, Shares Issued, Shares Acquired on Exchange [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	750,000	625,000	750,000	773,000
Stock Issued During Period, Shares, Stock Options Exercised	42,000		43,000		504,000