Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Real Estate [Abstract]
Land and land improvements	$ 1,218,906	$ 1,189,760
Building and improvements	5,352,219	5,343,908
Less accumulated depreciation	(1,228,702)	(1,182,569)
Operating real estate	5,342,423	5,351,099
Development in progress	338,673	277,411
Land held for development	291,159	269,059
Net real estate	5,972,255	5,897,569
Cash and cash equivalents	48,652	69,346
Restricted cash	14,939	20,325
Accounts receivable	14,384	15,481
Deferred rent receivable	119,224	107,909
Deferred financing and leasing costs, net of accumulated amortization (2015, $180,608; 2014, $169,468)	208,623	206,286
Investments in and advances to unconsolidated joint ventures	213,894	208,832
Assets held for sale	0	8,389
Prepaid expenses and other assets	97,822	91,399
Total assets	6,689,793	6,625,536
LIABILITIES
Mortgage loans	372,660	487,301
Unsecured notes	2,608,307	2,509,094
Credit facility	300,000	167,000
Accounts payable	60,256	52,043
Accrued interest	43,771	24,513
Dividend and distributions payable	71,863	72,253
Other liabilities	218,290	219,418
Total liabilities	3,675,147	3,531,622
Noncontrolling interest - operating partnership - 301,483 preferred units outstanding as of September 30, 2015 and December 31, 2014	7,537	7,537
EQUITY
Common shares of beneficial interest, $.001 par value, 283,987,000 shares authorized; 147,753,980 and 148,557,270 shares issued and outstanding as of September 30, 2015 and December 31, 2014, respectively	148	149
Additional paid-in capital	3,673,001	3,688,644
Accumulated other comprehensive loss	(13,837)	(6,252)
Distributions in excess of net income	(709,091)	(654,869)
Total Liberty Property Trust shareholders' equity	2,950,221	3,027,672
Noncontrolling interest - operating partnership
Noncontrolling interest - operating partnerships	52,969	54,786
Noncontrolling interest - consolidated joint ventures	3,919	3,919
Total owners' equity	3,007,109	3,086,377
Total liabilities, noncontrolling interest - operating partnership and equity	6,689,793	6,625,536
Liberty Property Limited Partnership [Member]
Real Estate [Abstract]
Land and land improvements	1,218,906	1,189,760
Building and improvements	5,352,219	5,343,908
Less accumulated depreciation	(1,228,702)	(1,182,569)
Operating real estate	5,342,423	5,351,099
Development in progress	338,673	277,411
Land held for development	291,159	269,059
Net real estate	5,972,255	5,897,569
Cash and cash equivalents	48,652	69,346
Restricted cash	14,939	20,325
Accounts receivable	14,384	15,481
Deferred rent receivable	119,224	107,909
Deferred financing and leasing costs, net of accumulated amortization (2015, $180,608; 2014, $169,468)	208,623	206,286
Investments in and advances to unconsolidated joint ventures	213,894	208,832
Assets held for sale	0	8,389
Prepaid expenses and other assets	97,822	91,399
Total assets	6,689,793	6,625,536
LIABILITIES
Mortgage loans	372,660	487,301
Unsecured notes	2,608,307	2,509,094
Credit facility	300,000	167,000
Accounts payable	60,256	52,043
Accrued interest	43,771	24,513
Dividend and distributions payable	71,863	72,253
Other liabilities	218,290	219,418
Total liabilities	3,675,147	3,531,622
Noncontrolling interest - operating partnership - 301,483 preferred units outstanding as of September 30, 2015 and December 31, 2014	7,537	7,537
EQUITY
General partner’s equity - 147,753,980 and 148,557,270 common units outstanding as of September 30, 2015 and December 31, 2014, respectively	2,950,221	3,027,672
Limited partners' equity	52,969	54,786
Noncontrolling interest - operating partnership
Noncontrolling interest - consolidated joint ventures	3,919	3,919
Total owners' equity	3,007,109	3,086,377
Total liabilities, noncontrolling interest - operating partnership and equity	$ 6,689,793	$ 6,625,536