Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
ASSETS
Land and land improvements	$ 865,657	$ 852,785
Building and improvements	4,156,848	4,092,056
Less accumulated depreciation	(1,135,002)	(1,047,336)
Operating real estate	3,887,503	3,897,505
Development in progress	249,129	88,848
Land held for development	227,469	219,375
Net real estate	4,364,101	4,205,728
Cash and cash equivalents	34,069	18,204
Restricted cash	37,972	63,659
Accounts receivable	6,965	8,192
Deferred rent receivable	107,813	102,613
Deferred financing and leasing costs, net of accumulated amortization	130,761	129,614
Investments in and advances to unconsolidated joint ventures	169,507	174,687
Assets held for sale	8,671	210,790
Prepaid expenses and other assets	96,506	76,186
Total assets	4,956,365	4,989,673
LIABILITIES
Mortgage loans	290,197	290,819
Unsecured notes	1,962,543	1,792,643
Credit facility	150,000	139,400
Accounts payable	58,804	23,418
Accrued interest	36,177	24,147
Dividend and distributions payable	58,869	56,958
Other liabilities	173,758	194,995
Total liabilities	2,730,348	2,522,380
Noncontrolling Interest - operating partnership	7,537	7,537
EQUITY
Common shares of beneficial interest	119	117
Additional paid-in capital	2,669,676	2,617,355
Accumulated other comprehensive loss	2,523	(429)
Distributions in excess of net income	(529,913)	(461,498)
Common shares in treasury, at cost	(51,951)	(51,951)
Total Liberty Property Trust shareholders' equity	2,090,454	2,103,594
Noncontrolling interest - operating partnership
Noncontrolling interest - consolidated joint ventures	3,775	3,775
Total equity	2,218,480	2,459,756
Total liabilities, noncontrolling interest - operating partnership and equity	4,956,365	4,989,673
common units outstanding
Noncontrolling interest - operating partnership
Noncontrolling interest - operating partnerships	60,987	64,428
preferred units outstanding
Noncontrolling interest - operating partnership
Noncontrolling interest - operating partnerships	63,264	287,959
Liberty Property Limited Partnership [Member]
ASSETS
Land and land improvements	865,657	852,785
Building and improvements	4,156,848	4,092,056
Less accumulated depreciation	(1,135,002)	(1,047,336)
Operating real estate	3,887,503	3,897,505
Development in progress	249,129	88,848
Land held for development	227,469	219,375
Net real estate	4,364,101	4,205,728
Cash and cash equivalents	34,069	18,204
Restricted cash	37,972	63,659
Accounts receivable	6,965	8,192
Deferred rent receivable	107,813	102,613
Deferred financing and leasing costs, net of accumulated amortization	130,761	129,614
Investments in and advances to unconsolidated joint ventures	169,507	174,687
Assets held for sale	8,671	210,790
Prepaid expenses and other assets	96,506	76,186
Total assets	4,956,365	4,989,673
LIABILITIES
Mortgage loans	290,197	290,819
Unsecured notes	1,962,543	1,792,643
Credit facility	150,000	139,400
Accounts payable	58,804	23,418
Accrued interest	36,177	24,147
Dividend and distributions payable	58,869	56,958
Other liabilities	173,758	194,995
Total liabilities	2,730,348	2,522,380
Noncontrolling Interest - operating partnership	7,537	7,537
EQUITY
General patner's equity	2,090,454	2,103,594
Noncontrolling interest - operating partnership
Noncontrolling interest - consolidated joint ventures	3,775	3,775
Total equity	2,218,480	2,459,756
Total liabilities, noncontrolling interest - operating partnership and equity	4,956,365	4,989,673
Liberty Property Limited Partnership [Member] | common units outstanding
EQUITY
Limited partners' equity	60,987	64,428
Liberty Property Limited Partnership [Member] | preferred units outstanding
EQUITY
Limited partners' equity	$ 63,264	$ 287,959