Consolidated Statements of Cash Flows (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
OPERATING ACTIVITIES
Net income	$ 169,465	$ 116,842
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	128,828	130,158
Amortization of deferred financing costs	3,948	4,735
Equity in earnings of unconsolidated joint ventures	(2,470)	(1,562)
Distributions from unconsolidated joint ventures	350	517
Gain on property dispositions	(58,083)	(9,192)
Noncash compensation	8,052	10,011
Changes in operating assets and liabilities:
Restricted cash	(16,792)	744
Accounts receivable	(2,370)	(3,553)
Deferred rent receivable	(5,361)	(11,124)
Prepaid expenses and other assets	(4,037)	(18,431)
Accounts payable	16,602	11,669
Accrued interest	3,236	(5,336)
Other liabilities	(2,936)	(5,984)
Net cash provided by operating activities	238,432	219,494
INVESTING ACTIVITIES
Investment in properties - acquisitions	(124,823)	(35,080)
Investment in properties - other	(51,615)	(56,325)
Investments in and advances to unconsolidated joint ventures	(11,309)	(1,426)
Distributions from unconsolidated joint ventures	9,257	4,774
Net proceeds from disposition of properties/land	361,154	23,990
Net proceeds from public reimbursement receivable/escrow	(18,274)	20,609
Investment in development in progress	(25,194)	(7,481)
Investment in land held for development	(18,475)	(4,779)
Investment in deferred leasing costs	(16,662)	(22,991)
Net cash provided by (used in) investing activities	104,059	(78,709)
FINANCING ACTIVITIES
Net proceeds from issuance of Common Shares	33,396	22,123
Proceeds from Issuance of Unsecured Debt	0	350,000
Repayments of unsecured notes	(246,500)	(169,739)
Proceeds from mortgage loans	0	743
Repayments of mortgage loans	(28,407)	(136,331)
Proceeds from credit facility	302,900	338,500
Repayments on credit facility	(302,900)	(478,500)
Increase in deferred financing costs	(13)	(9,217)
Distribution paid on Common Shares	(163,658)	(161,043)
Distribution paid on units	(21,317)	(21,570)
Net cash used in financing activities	(426,499)	(265,034)
Net decrease in cash and cash equivalents	(84,008)	(124,249)
Increase (decrease) in cash and cash equivalents related to foreign currency translation	15	(1,256)
Cash and cash equivalents at beginning of period	108,409	237,446
Cash and cash equivalents at end of period	24,416	111,941
Liberty Property Limited Partnership [Member]
OPERATING ACTIVITIES
Net income	169,465	116,842
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	128,828	130,158
Amortization of deferred financing costs	3,948	4,735
Equity in earnings of unconsolidated joint ventures	(2,470)	(1,562)
Distributions from unconsolidated joint ventures	350	517
Gain on property dispositions	(58,083)	(9,192)
Noncash compensation	8,052	10,011
Changes in operating assets and liabilities:
Restricted cash	(16,792)	744
Accounts receivable	(2,370)	(3,553)
Deferred rent receivable	(5,361)	(11,124)
Prepaid expenses and other assets	(4,037)	(18,431)
Accounts payable	16,602	11,669
Accrued interest	3,236	(5,336)
Other liabilities	(2,936)	(5,984)
Net cash provided by operating activities	238,432	219,494
INVESTING ACTIVITIES
Investment in properties - acquisitions	(124,823)	(35,080)
Investment in properties - other	(51,615)	(56,325)
Investments in and advances to unconsolidated joint ventures	(11,309)	(1,426)
Distributions from unconsolidated joint ventures	9,257	4,774
Net proceeds from disposition of properties/land	361,154	23,990
Net proceeds from public reimbursement receivable/escrow	(18,274)	20,609
Investment in development in progress	(25,194)	(7,481)
Investment in land held for development	(18,475)	(4,779)
Investment in deferred leasing costs	(16,662)	(22,991)
Net cash provided by (used in) investing activities	104,059	(78,709)
FINANCING ACTIVITIES
Proceeds from Issuance of Unsecured Debt	0	350,000
Repayments of unsecured notes	(246,500)	(169,739)
Proceeds from mortgage loans	0	743
Repayments of mortgage loans	(28,407)	(136,331)
Proceeds from credit facility	302,900	338,500
Repayments on credit facility	(302,900)	(478,500)
Increase in deferred financing costs	(13)	(9,217)
Capital contributions	33,396	22,123
Distributions to partners	(184,975)	(182,613)
Net cash used in financing activities	(426,499)	(265,034)
Net decrease in cash and cash equivalents	(84,008)	(124,249)
Increase (decrease) in cash and cash equivalents related to foreign currency translation	15	(1,256)
Cash and cash equivalents at beginning of period	108,409	237,446
Cash and cash equivalents at end of period	$ 24,416	$ 111,941