Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
OPERATING ACTIVITIES
Net income	$ 143,725	$ 44,244
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	45,144	45,992
Amortization of deferred financing costs	967	937
Expensed pursuit costs	324	32
Equity in earnings of unconsolidated joint ventures	(6,764)	(5,731)
Gain on property dispositions	(94,170)	(807)
Share-based compensation/Non-cash compensation	9,633	7,971
Other	2,206	(844)
Changes in operating assets and liabilities:
Accounts receivable	(706)	36
Deferred rent receivable	(4,944)	(5,566)
Prepaid expenses and other assets	20,312	6,824
Accounts payable	(9,003)	(7,136)
Accrued interest	13,059	12,972
Other liabilities	(26,084)	(14,444)
Net cash provided by operating activities	93,699	84,480
INVESTING ACTIVITIES
Investment in properties - acquisitions	(95,027)	0
Investment in properties - other	(3,603)	(12,422)
Investments in and advances to unconsolidated joint ventures	(66,420)	(13,278)
Distributions from unconsolidated joint ventures	11,521	9,427
Net proceeds from disposition of properties/land	184,233	1,874
Investment in development in progress	(51,932)	(64,661)
Investment in land held for development	(18,234)	(53,660)
Payment of deferred leasing costs	(2,183)	(7,544)
Release of escrows and other	126,745	9,016
Net cash provided by (used in) investing activities	85,100	(131,248)
FINANCING ACTIVITIES
Net proceeds from issuance of common shares	3,267	852
Share repurchase including shares related to tax withholdings	(4,402)	(4,624)
Repayments of mortgage loans	(1,714)	(1,930)
Proceeds from credit facility	312,993	159,000
Repayments on credit facility	(414,757)	(44,000)
Distribution paid on common shares	(58,980)	(69,823)
Distributions to partners/noncontrolling interests	(1,651)	(1,987)
Net cash (used in) provided by financing activities	(165,244)	37,488
Net increase (decrease) in cash, cash equivalents and restricted cash	13,555	(9,280)
Increase in cash, cash equivalents and restricted cash related to foreign currency translation	506	470
Cash, cash equivalents and restricted cash at beginning of period	25,685	56,025
Cash, cash equivalents and restricted cash at end of period	39,746	47,215
Liberty Property Limited Partnership [Member]
OPERATING ACTIVITIES
Net income	143,725	44,244
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	45,144	45,992
Amortization of deferred financing costs	967	937
Expensed pursuit costs	324	32
Equity in earnings of unconsolidated joint ventures	(6,764)	(5,731)
Gain on property dispositions	(94,170)	(807)
Share-based compensation/Non-cash compensation	9,633	7,971
Other	2,206	(844)
Changes in operating assets and liabilities:
Accounts receivable	(706)	36
Deferred rent receivable	(4,944)	(5,566)
Prepaid expenses and other assets	20,312	6,824
Accounts payable	(9,003)	(7,136)
Accrued interest	13,059	12,972
Other liabilities	(26,084)	(14,444)
Net cash provided by operating activities	93,699	84,480
INVESTING ACTIVITIES
Investment in properties - acquisitions	(95,027)	0
Investment in properties - other	(3,603)	(12,422)
Investments in and advances to unconsolidated joint ventures	(66,420)	(13,278)
Distributions from unconsolidated joint ventures	11,521	9,427
Net proceeds from disposition of properties/land	184,233	1,874
Investment in development in progress	(51,932)	(64,661)
Investment in land held for development	(18,234)	(53,660)
Payment of deferred leasing costs	(2,183)	(7,544)
Release of escrows and other	126,745	9,016
Net cash provided by (used in) investing activities	85,100	(131,248)
FINANCING ACTIVITIES
Repayments of mortgage loans	(1,714)	(1,930)
Proceeds from credit facility	312,993	159,000
Repayments on credit facility	(414,757)	(44,000)
Capital contributions	3,267	852
Distributions to partners/noncontrolling interests	(65,033)	(76,434)
Net cash (used in) provided by financing activities	(165,244)	37,488
Net increase (decrease) in cash, cash equivalents and restricted cash	13,555	(9,280)
Increase in cash, cash equivalents and restricted cash related to foreign currency translation	506	470
Cash, cash equivalents and restricted cash at beginning of period	25,685	56,025
Cash, cash equivalents and restricted cash at end of period	$ 39,746	$ 47,215