Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
OPERATING ACTIVITIES
Net income	$ 117,899	$ 77,282
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	90,956	82,963
Amortization of deferred financing costs	2,348	2,397
Equity in earnings of unconsolidated joint ventures	(3,323)	(1,685)
Distributions from unconsolidated joint ventures	470	208
Gain on property dispositions	(54,209)	(4,903)
Share-based compensation	6,359	6,437
Changes in operating assets and liabilities:
Restricted cash	5,478	24,101
Accounts receivable	875	(4,241)
Deferred rent receivable	(4,197)	(3,398)
Prepaid expenses and other assets	1,477	(1,526)
Accounts payable	1,161	12,196
Accrued interest	(158)	1,049
Other liabilities	(18,727)	(30,230)
Net cash provided by operating activities	146,409	160,650
INVESTING ACTIVITIES
Investment in operating properties - acquisitions	(133,500)	(29,294)
Investment in operating properties - other	(24,104)	(27,898)
Investments in and advances to unconsolidated joint ventures	(8,153)	(2,575)
Distributions from unconsolidated joint ventures	4,975	5,472
Net proceeds from disposition of properties/land	124,453	214,877
Net proceeds from (advances on) public reimbursement receivable/escrow	10,845	(78)
Investment in development in progress	(47,843)	(97,062)
Investment in land held for development	(13,586)	(10,791)
Investment in deferred leasing costs	(15,166)	(14,448)
Net cash (used in) provided by investing activities	(102,079)	38,203
FINANCING ACTIVITIES
Net proceeds from issuance of common shares	108,852	31,234
Redemption of preferred units	(64,500)	(221,000)
Proceeds from unsecured notes	0	400,000
Proceeds from mortgage loans	6,738	17,311
Repayments of mortgage loans	(2,506)	(26,960)
Proceeds from credit facility	269,550	453,200
Repayments on credit facility	(216,550)	(592,600)
Increase in deferred financing costs	(8)	(4,272)
Distribution paid on common shares	(113,241)	(110,731)
Distribution paid on units	(5,827)	(10,130)
Net cash used in financing activities	(17,492)	(63,948)
Net increase in cash and cash equivalents	26,838	134,905
(Decrease) increase in cash and cash equivalents related to foreign currency translation	(3,515)	1,013
Cash and cash equivalents at beginning of period	38,356	18,204
Cash and cash equivalents at end of period	61,679	154,122
Liberty Property Limited Partnership [Member]
OPERATING ACTIVITIES
Net income	117,899	77,282
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	90,956	82,963
Amortization of deferred financing costs	2,348	2,397
Equity in earnings of unconsolidated joint ventures	(3,323)	(1,685)
Distributions from unconsolidated joint ventures	470	208
Gain on property dispositions	(54,209)	(4,903)
Share-based compensation	6,359	6,437
Changes in operating assets and liabilities:
Restricted cash	5,478	24,101
Accounts receivable	875	(4,241)
Deferred rent receivable	(4,197)	(3,398)
Prepaid expenses and other assets	1,477	(1,526)
Accounts payable	1,161	12,196
Accrued interest	(158)	1,049
Other liabilities	(18,727)	(30,230)
Net cash provided by operating activities	146,409	160,650
INVESTING ACTIVITIES
Investment in operating properties - acquisitions	(133,500)	(29,294)
Investment in operating properties - other	(24,104)	(27,898)
Investments in and advances to unconsolidated joint ventures	(8,153)	(2,575)
Distributions from unconsolidated joint ventures	4,975	5,472
Net proceeds from disposition of properties/land	124,453	214,877
Net proceeds from (advances on) public reimbursement receivable/escrow	10,845	(78)
Investment in development in progress	(47,843)	(97,062)
Investment in land held for development	(13,586)	(10,791)
Investment in deferred leasing costs	(15,166)	(14,448)
Net cash (used in) provided by investing activities	(102,079)	38,203
FINANCING ACTIVITIES
Redemption of preferred units	(64,500)	(221,000)
Proceeds from unsecured notes	0	400,000
Proceeds from mortgage loans	6,738	17,311
Repayments of mortgage loans	(2,506)	(26,960)
Proceeds from credit facility	269,550	453,200
Repayments on credit facility	(216,550)	(592,600)
Increase in deferred financing costs	(8)	(4,272)
Capital contributions	108,852	31,234
Distributions to partners	(119,068)	(120,861)
Net cash used in financing activities	(17,492)	(63,948)
Net increase in cash and cash equivalents	26,838	134,905
(Decrease) increase in cash and cash equivalents related to foreign currency translation	(3,515)	1,013
Cash and cash equivalents at beginning of period	38,356	18,204
Cash and cash equivalents at end of period	$ 61,679	$ 154,122