Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
OPERATING ACTIVITIES
Net income	$ 74,656	$ 39,602
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	45,585	41,778
Amortization of deferred financing costs	1,168	1,188
Equity in earnings of unconsolidated joint ventures	(1,757)	(916)
Distributions from unconsolidated joint ventures	265	208
Gain on property dispositions	(43,513)	(1,587)
Share-based compensation	4,445	4,310
Changes in operating assets and liabilities:
Restricted cash	4,639	24,604
Accounts receivable	642	(1,022)
Deferred rent receivable	(3,246)	(1,484)
Prepaid expenses and other assets	1,319	(6,578)
Accounts payable	1,136	8,893
Accrued interest	18,867	8,889
Other liabilities	(12,002)	(25,163)
Net cash provided by operating activities	92,204	92,722
INVESTING ACTIVITIES
Investment in operating properties - other	(6,794)	(13,243)
Investments in and advances to unconsolidated joint ventures	(6,379)	(2,702)
Distributions from unconsolidated joint ventures	1,871	3,610
Net proceeds from disposition of properties/land	71,909	6,237
Net proceeds from (advances on) public reimbursement receivable/escrow	8,500	(6,925)
Investment in development in progress	(27,509)	(43,405)
Investment in land held for development	(3,493)	(2,648)
Investment in deferred leasing costs	(7,387)	(7,983)
Net cash provided by (used in) investing activities	30,718	(67,059)
FINANCING ACTIVITIES
Net proceeds from issuance of common shares	44,927	16,197
Repayments of unsecured notes	0	(121,000)
Proceeds from mortgage loans	3,261	11,186
Repayments of mortgage loans	(1,249)	(19,288)
Proceeds from credit facility	19,600	259,650
Repayments on credit facility	(111,600)	(105,750)
Increase in deferred financing costs	(4)	(285)
Distribution paid on Common Shares	(56,274)	(55,149)
Distribution paid on units	(1,961)	(3,883)
Net cash used in financing activities	(103,300)	(18,322)
Net increase in cash and cash equivalents	19,622	7,341
(Decrease) increase in cash and cash equivalents related to foreign currency translation	(3,544)	2,105
Cash and cash equivalents at beginning of period	38,356	18,204
Cash and cash equivalents at end of period	54,434	27,650
Liberty Property Limited Partnership [Member]
OPERATING ACTIVITIES
Net income	74,656	39,602
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	45,585	41,778
Amortization of deferred financing costs	1,168	1,188
Equity in earnings of unconsolidated joint ventures	(1,757)	(916)
Distributions from unconsolidated joint ventures	265	208
Gain on property dispositions	(43,513)	(1,587)
Share-based compensation	4,445	4,310
Changes in operating assets and liabilities:
Restricted cash	4,639	24,604
Accounts receivable	642	(1,022)
Deferred rent receivable	(3,246)	(1,484)
Prepaid expenses and other assets	1,319	(6,578)
Accounts payable	1,136	8,893
Accrued interest	18,867	8,889
Other liabilities	(12,002)	(25,163)
Net cash provided by operating activities	92,204	92,722
INVESTING ACTIVITIES
Investment in operating properties - other	(6,794)	(13,243)
Investments in and advances to unconsolidated joint ventures	(6,379)	(2,702)
Distributions from unconsolidated joint ventures	1,871	3,610
Net proceeds from disposition of properties/land	71,909	6,237
Net proceeds from (advances on) public reimbursement receivable/escrow	8,500	(6,925)
Investment in development in progress	(27,509)	(43,405)
Investment in land held for development	(3,493)	(2,648)
Investment in deferred leasing costs	(7,387)	(7,983)
Net cash provided by (used in) investing activities	30,718	(67,059)
FINANCING ACTIVITIES
Repayments of unsecured notes	0	(121,000)
Proceeds from mortgage loans	3,261	11,186
Repayments of mortgage loans	(1,249)	(19,288)
Proceeds from credit facility	19,600	259,650
Repayments on credit facility	(111,600)	(105,750)
Increase in deferred financing costs	(4)	(285)
Capital contributions	44,927	16,197
Distributions to partners	(58,235)	(59,032)
Net cash used in financing activities	(103,300)	(18,322)
Net increase in cash and cash equivalents	19,622	7,341
(Decrease) increase in cash and cash equivalents related to foreign currency translation	(3,544)	2,105
Cash and cash equivalents at beginning of period	38,356	18,204
Cash and cash equivalents at end of period	$ 54,434	$ 27,650