Income per Common Unit of the Operating Partnership (Tables)

12 Months Ended

Dec. 31, 2012

Income Per Common Unit [Line Items]

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	2012					2011
	Income (Numerator)		Weighted Average Shares (Denominator)	Per Share		Income (Numerator)		Weighted Average Shares (Denominator)	Per Share
Basic income from continuing operations
Income from continuing operations net of noncontrolling interest	$	123,945	116,863	$	1.06	$	115,653	114,755	$	1.00
Dilutive shares for long-term compensation plans	—		831			—		748
Diluted income from continuing operations
Income from continuing operations net of noncontrolling interest	123,945		117,694	$	1.06	115,653		115,503	$	1.00
Basic income from discontinued operations
Discontinued operations net of noncontrolling interest	13,491		116,863	$	0.12	68,346		114,755	$	0.60
Dilutive shares for long-term compensation plans	—		831			—		748
Diluted income from discontinued operations
Discontinued operations net of noncontrolling interest	13,491		117,694	$	0.11	68,346		115,503	$	0.59
Basic income per common share
Net income available to common shareholders	137,436		116,863	$	1.18	183,999		114,755	$	1.60
Dilutive shares for long-term compensation plans	—		831			—		748
Diluted income per common share
Net income available to common shareholders	$	137,436	117,694	$	1.17	$	183,999	115,503	$	1.59

	2010
	Income (Numerator)		Weighted Average Shares (Denominator)	Per Share
Basic income from continuing operations
Income from continuing operations net of noncontrolling interest	$	104,522	112,924	$	0.92
Dilutive shares for long-term compensation plans	—		682
Diluted income from continuing operations
Income from continuing operations net of noncontrolling interest	104,522		113,606	$	0.91
Basic income from discontinued operations
Discontinued operations net of noncontrolling interest	23,240		112,924	$	0.21
Dilutive shares for long-term compensation plans	—		682
Diluted income from discontinued operations
Discontinued operations net of noncontrolling interest	23,240		113,606	$	0.21
Basic income per common share
Net income available to common shareholders	127,762		112,924	$	1.13
Dilutive shares for long-term compensation plans	—		682
Diluted income per common share
Net income available to common shareholders	$	127,762	113,606	$	1.12

Liberty Property Limited Partnership [Member]

Income Per Common Unit [Line Items]

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	2012						2011
	Income (Numerator)			Weighted Average Units (Denominator)	Per Unit		Income (Numerator)			Weighted Average Units (Denominator)	Per Unit
Income from continuing operations net of noncontrolling interest	$	134,105					$	140,572
Less: Preferred unit distributions	(9,902		)				(21,069		)
Excess of preferred unit carrying amount over redemption	3,689						—
Basic income from continuing operations
Income from continuing operations available to common unitholders	127,892			120,623	$	1.06	119,503			118,624	$	1.00
Dilutive units for long-term compensation plans	—			831			—			748
Diluted income from continuing operations
Income from continuing operations available to common unitholders	127,892			121,454	$	1.06	119,503			119,372	$	1.00
Basic income from discontinued operations
Discontinued operations	13,921			120,623	$	0.12	70,649			118,624	$	0.60
Dilutive units for long-term compensation plans	—			831			—			748
Diluted income from discontinued operations
Discontinued operations	13,921			121,454	$	0.11	70,649			119,372	$	0.59
Basic income per common unit
Income available to common unitholders	141,813			120,623	$	1.18	190,152			118,624	$	1.60
Dilutive units for long-term compensation plans	—			831			—			748
Diluted income per common unit
Income available to common unitholders	$	141,813		121,454	$	1.17	$	190,152		119,372	$	1.59

	2010
	Income (Numerator)			Weighted Average Units (Denominator)	Per Unit
Income from continuing operations net of noncontrolling interest	$	129,975
Less: Preferred unit distributions	(21,012		)
Excess of preferred unit carrying amount over redemption	—
Basic income from continuing operations
Income from continuing operations available to common unitholders	108,963			116,871	$	0.92
Dilutive units for long-term compensation plans	—			682
Diluted income from continuing operations
Income from continuing operations available to common unitholders	108,963			117,553	$	0.91
Basic income from discontinued operations
Discontinued operations	23,235			116,871	$	0.21
Dilutive units for long-term compensation plans	—			682
Diluted income from discontinued operations
Discontinued operations	23,235			117,553	$	0.21
Basic income per common unit
Income available to common unitholders	132,198			116,871	$	1.13
Dilutive units for long-term compensation plans	—			682
Diluted income per common unit
Income available to common unitholders	$	132,198		117,553	$	1.12