Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
OPERATING ACTIVITIES
Net income	$ 219,594	$ 147,751	$ 210,710
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	205,147	167,421	171,714
Amortization of deferred financing costs and noncash portion of interest	4,449	4,682	5,190
Equity in (earnings) loss of unconsolidated joint ventures	(6,067)	681	(3,496)
Distributions from unconsolidated joint ventures	844	624	551
Gain on property dispositions	(107,079)	(15,506)	(65,607)
Noncash compensation	9,976	10,057	10,555
Changes in operating assets and liabilities:
Restricted cash	(18,397)	30,713	(14,114)
Accounts receivable	(4,889)	(799)	(1,320)
Deferred rent receivable	(9,473)	(6,363)	(6,566)
Prepaid expenses and other assets	(22,424)	(10,871)	6,027
Accounts payable	15,703	7,641	(229)
Accrued interest	5,613	(3,983)	(5,674)
Other liabilities	22,968	(14,882)	9,983
Net cash provided by operating activities	315,965	317,166	317,724
INVESTING ACTIVITIES
Investment in properties - acquisitions	(1,429,822)	(211,894)	(233,568)
Investment in properties - other	(74,345)	(49,682)	(75,834)
Investments in and advances to unconsolidated joint ventures	(16,185)	(1,461)	(11,195)
Distributions from unconsolidated joint ventures	13,774	6,009	11,364
Net proceeds from disposition of properties/land	526,949	234,686	390,754
Net proceeds from (advances on) public reimbursement receivable/escrow	9,821	(986)	(10,237)
Investment in development in progress	(123,879)	(199,384)	(48,628)
Investment in land held for development	(67,326)	(67,513)	(52,868)
Investment in deferred leasing costs	(36,901)	(22,444)	(26,011)
Net cash used in investing activities	(1,197,914)	(312,669)	(56,223)
FINANCING ACTIVITIES
Net proceeds from issuance of Common Shares	969,468	58,710	44,552
Redemption of preferred units	(64,500)	(221,000)	(9,060)
Proceeds from unsecured notes	448,646	700,000	0
Repayments of unsecured notes	0	(230,100)	(246,500)
Proceeds from mortgage loans	10,401	34,599	0
Repayments of mortgage loans	(10,605)	(35,099)	(29,860)
Proceeds from credit facility	611,550	839,250	650,500
Repayments on credit facility	(703,550)	(886,650)	(511,100)
Increase in deferred financing costs	(5,866)	(7,206)	(3,023)
Distribution paid on Common Shares	(240,340)	(222,573)	(218,613)
Distribution paid on units	(9,438)	(17,241)	(28,409)
Net cash provided by (used in) financing activities	1,005,766	12,690	(351,513)
Net increase (decrease) in cash and cash equivalents	123,817	17,187	(90,012)
Increase (decrease) in cash and cash equivalents related to foreign currency translation	1,241	2,965	(193)
Cash and cash equivalents at beginning of year	38,356	18,204	108,409
Cash and cash equivalents at end of year	163,414	38,356	18,204
Liberty Property Limited Partnership [Member]
OPERATING ACTIVITIES
Net income	219,594	147,751	210,710
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	205,147	167,421	171,714
Amortization of deferred financing costs and noncash portion of interest	4,449	4,682	5,190
Equity in (earnings) loss of unconsolidated joint ventures	(6,067)	681	(3,496)
Distributions from unconsolidated joint ventures	844	624	551
Gain on property dispositions	(107,079)	(15,506)	(65,607)
Noncash compensation	9,976	10,057	10,555
Changes in operating assets and liabilities:
Restricted cash	(18,397)	30,713	(14,114)
Accounts receivable	(4,889)	(799)	(1,320)
Deferred rent receivable	(9,473)	(6,363)	(6,566)
Prepaid expenses and other assets	(22,424)	(10,871)	6,027
Accounts payable	15,703	7,641	(229)
Accrued interest	5,613	(3,983)	(5,674)
Other liabilities	22,968	(14,882)	9,983
Net cash provided by operating activities	315,965	317,166	317,724
INVESTING ACTIVITIES
Investment in properties - acquisitions	(1,429,822)	(211,894)	(233,568)
Investment in properties - other	(74,345)	(49,682)	(75,834)
Investments in and advances to unconsolidated joint ventures	(16,185)	(1,461)	(11,195)
Distributions from unconsolidated joint ventures	13,774	6,009	11,364
Net proceeds from disposition of properties/land	526,949	234,686	390,754
Net proceeds from (advances on) public reimbursement receivable/escrow	9,821	(986)	(10,237)
Investment in development in progress	(123,879)	(199,384)	(48,628)
Investment in land held for development	(67,326)	(67,513)	(52,868)
Investment in deferred leasing costs	(36,901)	(22,444)	(26,011)
Net cash used in investing activities	(1,197,914)	(312,669)	(56,223)
FINANCING ACTIVITIES
Redemption of preferred units	(64,500)	(221,000)	(9,060)
Proceeds from unsecured notes	448,646	700,000	0
Repayments of unsecured notes	0	(230,100)	(246,500)
Proceeds from mortgage loans	10,401	34,599	0
Repayments of mortgage loans	(10,605)	(35,099)	(29,860)
Proceeds from credit facility	611,550	839,250	650,500
Repayments on credit facility	(703,550)	(886,650)	(511,100)
Increase in deferred financing costs	(5,866)	(7,206)	(3,023)
Capital contributions	969,468	58,710	44,552
Distributions to partners	(249,778)	(239,814)	(247,022)
Net cash provided by (used in) financing activities	1,005,766	12,690	(351,513)
Net increase (decrease) in cash and cash equivalents	123,817	17,187	(90,012)
Increase (decrease) in cash and cash equivalents related to foreign currency translation	1,241	2,965	(193)
Cash and cash equivalents at beginning of year	38,356	18,204	108,409
Cash and cash equivalents at end of year	$ 163,414	$ 38,356	$ 18,204