Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
OPERATING ACTIVITIES
Net income	$ 77,282	$ 127,784
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	82,963	86,795
Amortization of deferred financing costs	2,397	2,735
Equity in earnings of unconsolidated joint ventures	(1,685)	(1,643)
Distributions from unconsolidated joint ventures	208	305
Gain on property dispositions	(4,903)	(52,090)
Noncash compensation	6,437	6,172
Changes in operating assets and liabilities:
Restricted cash	24,101	(462)
Accounts receivable	(4,241)	(879)
Deferred rent receivable	(3,398)	(4,526)
Prepaid expenses and other assets	(1,526)	16,803
Accounts payable	12,196	4,921
Accrued interest	1,049	(5,446)
Other liabilities	(30,230)	(13,754)
Net cash provided by operating activities	160,650	166,715
INVESTING ACTIVITIES
Investment in properties - acquisitions	(29,294)	(34,151)
Investment in properties - other	(27,898)	(33,107)
Investments in and advances to unconsolidated joint ventures	(2,575)	(8,382)
Distributions from unconsolidated joint ventures	5,472	6,391
Net proceeds from disposition of properties/land	214,877	264,419
Net proceeds from public reimbursement receivable/escrow	(78)	(56,395)
Investment in development in progress	(97,062)	(10,310)
Investment in land held for development	(10,791)	(5,116)
Investment in deferred leasing costs	(14,448)	(10,844)
Net cash provided by (used in) investing activities	38,203	112,505
FINANCING ACTIVITIES
Net proceeds from issuance of common shares	31,234	24,580
Payments for Repurchase of Redeemable Preferred Stock	(221,000)	0
Proceeds from unsecured notes	400,000	0
Repayments of unsecured notes	0	(246,500)
Proceeds from mortgage loans	17,311	0
Repayments of mortgage loans	(26,960)	(26,976)
Proceeds from credit facility	453,200	283,000
Repayments on credit facility	(592,600)	(250,000)
Increase in deferred financing costs	(4,272)	(13)
Distribution paid on Common Shares	(110,731)	(108,881)
Distribution paid on units	(10,130)	(14,442)
Net cash used in financing activities	(63,948)	(339,232)
Net decrease in cash and cash equivalents	134,905	(60,012)
Increase (decrease) in cash and cash equivalents related to foreign currency translation	1,013	1,498
Cash and cash equivalents at beginning of period	18,204	108,409
Cash and cash equivalents at end of period	154,122	49,895
Liberty Property Limited Partnership [Member]
OPERATING ACTIVITIES
Net income	77,282	127,784
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	82,963	86,795
Amortization of deferred financing costs	2,397	2,735
Equity in earnings of unconsolidated joint ventures	(1,685)	(1,643)
Distributions from unconsolidated joint ventures	208	305
Gain on property dispositions	(4,903)	(52,090)
Noncash compensation	6,437	6,172
Changes in operating assets and liabilities:
Restricted cash	24,101	(462)
Accounts receivable	(4,241)	(879)
Deferred rent receivable	(3,398)	(4,526)
Prepaid expenses and other assets	(1,526)	16,803
Accounts payable	12,196	4,921
Accrued interest	1,049	(5,446)
Other liabilities	(30,230)	(13,754)
Net cash provided by operating activities	160,650	166,715
INVESTING ACTIVITIES
Investment in properties - acquisitions	(29,294)	(34,151)
Investment in properties - other	(27,898)	(33,107)
Investments in and advances to unconsolidated joint ventures	(2,575)	(8,382)
Distributions from unconsolidated joint ventures	5,472	6,391
Net proceeds from disposition of properties/land	214,877	264,419
Net proceeds from public reimbursement receivable/escrow	(78)	(56,395)
Investment in development in progress	(97,062)	(10,310)
Investment in land held for development	(10,791)	(5,116)
Investment in deferred leasing costs	(14,448)	(10,844)
Net cash provided by (used in) investing activities	38,203	112,505
FINANCING ACTIVITIES
Payments for Repurchase of Redeemable Preferred Stock	(221,000)	0
Proceeds from unsecured notes	400,000	0
Repayments of unsecured notes	0	(246,500)
Proceeds from mortgage loans	17,311	0
Repayments of mortgage loans	(26,960)	(26,976)
Proceeds from credit facility	453,200	283,000
Repayments on credit facility	(592,600)	(250,000)
Increase in deferred financing costs	(4,272)	(13)
Capital contributions	31,234	24,580
Distributions to partners	(120,861)	(123,323)
Net cash used in financing activities	(63,948)	(339,232)
Net decrease in cash and cash equivalents	134,905	(60,012)
Increase (decrease) in cash and cash equivalents related to foreign currency translation	1,013	1,498
Cash and cash equivalents at beginning of period	18,204	108,409
Cash and cash equivalents at end of period	$ 154,122	$ 49,895