Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
OPERATING ACTIVITIES
Net income	$ 39,602	$ 34,943
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	41,778	44,764
Amortization of deferred financing costs	1,188	1,521
Equity in earnings of unconsolidated joint ventures	(916)	(534)
Distributions from unconsolidated joint ventures	208	305
Gain on property dispositions	(1,587)	(1,631)
Noncash compensation	4,310	4,494
Changes in operating assets and liabilities:
Restricted cash	24,604	(5,196)
Accounts receivable	(1,022)	(4,804)
Deferred rent receivable	(1,484)	(2,678)
Prepaid expenses and other assets	(6,578)	4,216
Accounts payable	8,893	3,177
Accrued interest	8,889	3,656
Other liabilities	(25,163)	(6,246)
Net cash provided by operating activities	92,722	75,987
INVESTING ACTIVITIES
Investment in properties - other	(13,243)	(19,058)
Investments in and advances to unconsolidated joint ventures	(2,702)	(6,507)
Distributions from unconsolidated joint ventures	3,610	2,258
Net proceeds from disposition of properties/land	6,237	3,451
Net proceeds from public reimbursement receivable/escrow	(6,925)	(631)
Investment in development in progress	(43,405)	(4,093)
Investment in land held for development	(2,648)	(1,410)
Investment in deferred leasing costs	(7,983)	(5,790)
Net cash provided by (used in) investing activities	(67,059)	(31,780)
FINANCING ACTIVITIES
Net proceeds from issuance of Common Shares	16,197	12,085
Payments for Repurchase of Redeemable Preferred Stock	(121,000)	0
Repayments of unsecured notes	0	(246,500)
Proceeds from mortgage loans	11,186	0
Repayments of mortgage loans	(19,288)	(25,558)
Proceeds from credit facility	259,650	200,000
Repayments on credit facility	(105,750)	0
Increase in deferred financing costs	(285)	(12)
Distribution paid on Common Shares	(55,149)	(54,284)
Distribution paid on units	(3,883)	(7,108)
Net cash used in financing activities	(18,322)	(121,377)
Net decrease in cash and cash equivalents	7,341	(77,170)
Increase (decrease) in cash and cash equivalents related to foreign currency translation	2,105	1,472
Cash and cash equivalents at beginning of period	18,204	108,409
Cash and cash equivalents at end of period	27,650	32,711
Liberty Property Limited Partnership [Member]
OPERATING ACTIVITIES
Net income	39,602	34,943
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	41,778	44,764
Amortization of deferred financing costs	1,188	1,521
Equity in earnings of unconsolidated joint ventures	(916)	(534)
Distributions from unconsolidated joint ventures	208	305
Gain on property dispositions	(1,587)	(1,631)
Noncash compensation	4,310	4,494
Changes in operating assets and liabilities:
Restricted cash	24,604	(5,196)
Accounts receivable	(1,022)	(4,804)
Deferred rent receivable	(1,484)	(2,678)
Prepaid expenses and other assets	(6,578)	4,216
Accounts payable	8,893	3,177
Accrued interest	8,889	3,656
Other liabilities	(25,163)	(6,246)
Net cash provided by operating activities	92,722	75,987
INVESTING ACTIVITIES
Investment in properties - other	(13,243)	(19,058)
Investments in and advances to unconsolidated joint ventures	(2,702)	(6,507)
Distributions from unconsolidated joint ventures	3,610	2,258
Net proceeds from disposition of properties/land	6,237	3,451
Net proceeds from public reimbursement receivable/escrow	(6,925)	(631)
Investment in development in progress	(43,405)	(4,093)
Investment in land held for development	(2,648)	(1,410)
Investment in deferred leasing costs	(7,983)	(5,790)
Net cash provided by (used in) investing activities	(67,059)	(31,780)
FINANCING ACTIVITIES
Payments for Repurchase of Redeemable Preferred Stock	(121,000)	0
Repayments of unsecured notes	0	(246,500)
Proceeds from mortgage loans	11,186	0
Repayments of mortgage loans	(19,288)	(25,558)
Proceeds from credit facility	259,650	200,000
Repayments on credit facility	(105,750)	0
Increase in deferred financing costs	(285)	(12)
Capital contributions	16,197	12,085
Distributions to partners	(59,032)	(61,392)
Net cash used in financing activities	(18,322)	(121,377)
Net decrease in cash and cash equivalents	7,341	(77,170)
Increase (decrease) in cash and cash equivalents related to foreign currency translation	2,105	1,472
Cash and cash equivalents at beginning of period	18,204	108,409
Cash and cash equivalents at end of period	$ 27,650	$ 32,711