Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
OPERATING ACTIVITIES
Net income	$ 147,847	$ 107,180
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	137,302	124,420
Amortization of deferred financing costs	3,533	3,581
Equity in (earnings) loss of unconsolidated joint ventures	(3,973)	1,397
Distributions from unconsolidated joint ventures	613	536
Gain on property dispositions	(56,196)	(5,364)
Share-based compensation	8,174	8,307
Changes in operating assets and liabilities:
Restricted cash	(2,703)	25,864
Accounts receivable	231	1,223
Deferred rent receivable	(6,171)	(5,550)
Prepaid expenses and other assets	(50,389)	(19,626)
Accounts payable	15,494	35,389
Accrued interest	18,922	12,030
Other liabilities	2,352	(30,356)
Net cash provided by operating activities	215,036	259,031
INVESTING ACTIVITIES
Investment in operating properties - acquisitions	(161,404)	(35,644)
Investment in operating properties - other	(40,433)	(45,221)
Investments in and advances to unconsolidated joint ventures	(11,736)	(3,529)
Distributions from unconsolidated joint ventures	6,825	6,967
Net proceeds from disposition of properties/land	134,024	217,430
Net proceeds from (advances on) public reimbursement receivable/escrow	12,943	(682)
Investment in development in progress	(81,736)	(152,523)
Investment in land held for development	(34,642)	(32,871)
Investment in deferred leasing costs	(22,996)	(17,470)
Net cash used in investing activities	(199,155)	(63,543)
FINANCING ACTIVITIES
Net proceeds from issuance of common shares	954,481	42,808
Redemption of preferred units	(64,500)	(221,000)
Proceeds from unsecured notes	448,646	399,220
Repayments of unsecured notes	0	(230,100)
Proceeds from mortgage loans	10,401	27,481
Repayments of mortgage loans	(3,977)	(28,103)
Proceeds from credit facility	344,050	653,350
Repayments on credit facility	(436,050)	(642,750)
Increase in deferred financing costs	(3,883)	(3,498)
Distribution paid on common shares	(170,970)	(166,564)
Distribution paid on units	(7,619)	(13,139)
Net cash provided by (used in) financing activities	1,070,579	(182,295)
Net increase in cash and cash equivalents	1,086,460	13,193
(Decrease) increase in cash and cash equivalents related to foreign currency translation	(246)	2,672
Cash and cash equivalents at beginning of period	38,356	18,204
Cash and cash equivalents at end of period	1,124,570	34,069
Liberty Property Limited Partnership [Member]
OPERATING ACTIVITIES
Net income	147,847	107,180
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	137,302	124,420
Amortization of deferred financing costs	3,533	3,581
Equity in (earnings) loss of unconsolidated joint ventures	(3,973)	1,397
Distributions from unconsolidated joint ventures	613	536
Gain on property dispositions	(56,196)	(5,364)
Share-based compensation	8,174	8,307
Changes in operating assets and liabilities:
Restricted cash	(2,703)	25,864
Accounts receivable	231	1,223
Deferred rent receivable	(6,171)	(5,550)
Prepaid expenses and other assets	(50,389)	(19,626)
Accounts payable	15,494	35,389
Accrued interest	18,922	12,030
Other liabilities	2,352	(30,356)
Net cash provided by operating activities	215,036	259,031
INVESTING ACTIVITIES
Investment in operating properties - acquisitions	(161,404)	(35,644)
Investment in operating properties - other	(40,433)	(45,221)
Investments in and advances to unconsolidated joint ventures	(11,736)	(3,529)
Distributions from unconsolidated joint ventures	6,825	6,967
Net proceeds from disposition of properties/land	134,024	217,430
Net proceeds from (advances on) public reimbursement receivable/escrow	12,943	(682)
Investment in development in progress	(81,736)	(152,523)
Investment in land held for development	(34,642)	(32,871)
Investment in deferred leasing costs	(22,996)	(17,470)
Net cash used in investing activities	(199,155)	(63,543)
FINANCING ACTIVITIES
Redemption of preferred units	(64,500)	(221,000)
Proceeds from unsecured notes	448,646	399,220
Repayments of unsecured notes	0	(230,100)
Proceeds from mortgage loans	10,401	27,481
Repayments of mortgage loans	(3,977)	(28,103)
Proceeds from credit facility	344,050	653,350
Repayments on credit facility	(436,050)	(642,750)
Increase in deferred financing costs	(3,883)	(3,498)
Capital contributions	954,481	42,808
Distributions to partners	(178,589)	(179,703)
Net cash provided by (used in) financing activities	1,070,579	(182,295)
Net increase in cash and cash equivalents	1,086,460	13,193
(Decrease) increase in cash and cash equivalents related to foreign currency translation	(246)	2,672
Cash and cash equivalents at beginning of period	38,356	18,204
Cash and cash equivalents at end of period	$ 1,124,570	$ 34,069