Summary of Significant Accounting Policies (Adjustment of Previously Reported Financial Information, Comprehensive Income) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended			168 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Interest and other income									$ 13,950	$ 23,781	$ 17,600
Total other income (expense)									(128,226)	(111,998)	(134,287)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures									126,876	145,134	123,019
Income taxes									(1,971)	(2,673)	(2,590)
Income from continuing operations									366,145	245,924	175,890
Net income	$ 200,291	$ 55,734	$ 51,057	$ 59,063	$ 83,841	$ 93,695	$ 36,526	$ 31,862	366,145	245,924	224,471
Noncontrolling interest – operating partnership									(9,070)	(6,192)	(5,713)
Income available to common shareholders									356,817	239,483	218,211
Other comprehensive (loss) income - foreign currency translation									(34,744)	(12,540)	(15,671)
Other comprehensive loss									(34,334)	(13,028)	(17,632)
Total comprehensive income									331,811	232,896	206,839
Less: comprehensive income attributable to noncontrolling interest									(8,519)	(6,135)	(5,878)
Comprehensive income attributable to common shareholders									323,292	226,761	200,961
Income per common share - basic (USD per share/unit)	$ 1.33	$ 0.37	$ 0.34	$ 0.39	$ 0.56	$ 0.61	$ 0.24	$ 0.21
Income per common share - diluted (USD per share/unit)	$ 1.33	$ 0.37	$ 0.34	$ 0.39	$ 0.55	$ 0.61	$ 0.24	$ 0.21
Liberty Property Limited Partnership [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Interest and other income									13,950	23,781	17,600
Total other income (expense)									(128,226)	(111,998)	(134,287)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures									126,876	145,134	123,019
Income taxes									(1,971)	(2,673)	(2,590)
Income from continuing operations									366,145	245,924	175,890
Net income									366,145	245,924	224,471
Income available to common shareholders									365,415	245,203	223,452
Other comprehensive (loss) income - foreign currency translation									(34,744)	(12,540)	(15,671)
Other comprehensive loss									(34,334)	(13,028)	(17,632)
Total comprehensive income									331,811	232,896	206,839
Net income allocated to general partners									356,817	239,483	218,211
Net income allocated to limited partners									9,070	6,192	5,713
Restatement of Net Profit (Loss) [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Interest and other income										23,781	17,600
Total other income (expense)										(111,998)	(134,287)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures										145,134	123,019
Income taxes										(2,673)	(2,590)
Income from continuing operations										245,924	175,890
Net income										245,924	224,471
Noncontrolling interest – operating partnership										(6,192)	(5,713)
Income available to common shareholders										239,483	218,211
Other comprehensive (loss) income - foreign currency translation										(12,540)	(15,671)
Other comprehensive loss										(13,028)	(17,632)
Total comprehensive income										232,896	206,839
Less: comprehensive income attributable to noncontrolling interest										(6,135)	(5,878)
Comprehensive income attributable to common shareholders										$ 226,761	$ 200,961
Income from continuing operations (USD per share/unit)										$ 1.62	$ 1.16
Income per common share - basic (USD per share/unit)										$ 1.62	$ 1.48
Restatement of Net Profit (Loss) [Member] | Liberty Property Limited Partnership [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Interest and other income										$ 23,781	$ 17,600
Total other income (expense)										(111,998)	(134,287)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures										145,134	123,019
Income taxes										(2,673)	(2,590)
Income from continuing operations										245,924	175,890
Net income										245,924	224,471
Income available to common shareholders										245,203	223,452
Other comprehensive (loss) income - foreign currency translation										(12,540)	(15,671)
Other comprehensive loss										(13,028)	(17,632)
Total comprehensive income										$ 232,896	$ 206,839
Income from continuing operations (USD per share/unit)										$ 1.62	$ 1.16
Income per common share - basic (USD per share/unit)										$ 1.62	$ 1.48
Net income allocated to general partners										$ 239,483	$ 218,211
Net income allocated to limited partners										6,192	5,713
Previously Reported [Member] | Restatement of Net Profit (Loss) [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Interest and other income										22,863	17,669
Total other income (expense)										(112,916)	(134,218)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures										144,216	123,088
Income taxes										(3,233)	(2,967)
Income from continuing operations										244,446	175,582
Net income										244,446	224,163
Noncontrolling interest – operating partnership										(6,158)	(5,706)
Income available to common shareholders										238,039	217,910
Other comprehensive (loss) income - foreign currency translation										(11,433)	(14,415)
Other comprehensive loss										(11,921)	(16,376)
Total comprehensive income										232,525	207,787
Less: comprehensive income attributable to noncontrolling interest										(6,127)	(5,870)
Comprehensive income attributable to common shareholders										$ 226,398	$ 201,917
Income from continuing operations (USD per share/unit)										$ 1.61	$ 1.16
Income per common share - basic (USD per share/unit)										$ 1.61	$ 1.48
Previously Reported [Member] | Restatement of Net Profit (Loss) [Member] | Liberty Property Limited Partnership [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Interest and other income										$ 22,863	$ 17,669
Total other income (expense)										(112,916)	(134,218)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures										144,216	123,088
Income taxes										(3,233)	(2,967)
Income from continuing operations										244,446	175,582
Net income										244,446	224,163
Income available to common shareholders										243,725	223,144
Other comprehensive (loss) income - foreign currency translation										(11,433)	(14,415)
Other comprehensive loss										(11,921)	(16,376)
Total comprehensive income										$ 232,525	$ 207,787
Income from continuing operations (USD per share/unit)										$ 1.61	$ 1.16
Income per common share - basic (USD per share/unit)										$ 1.61	$ 1.48
Net income allocated to general partners										$ 238,039	$ 217,910
Net income allocated to limited partners										6,158	5,706
Adjustment [Member] | Restatement of Net Profit (Loss) [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Interest and other income										918	(69)
Total other income (expense)										918	(69)	$ 12,700
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures										918	(69)
Income taxes										560	377	$ 3,900
Income from continuing operations										1,478	308
Net income									$ (500)	1,478	308
Noncontrolling interest – operating partnership										(34)	(7)
Income available to common shareholders										1,444	301
Other comprehensive (loss) income - foreign currency translation										(1,107)	(1,256)
Other comprehensive loss										(1,107)	(1,256)
Total comprehensive income										371	(948)
Less: comprehensive income attributable to noncontrolling interest										(8)	(8)
Comprehensive income attributable to common shareholders										$ 363	$ (956)
Income from continuing operations (USD per share/unit)										$ 0.01	$ 0.00
Income per common share - basic (USD per share/unit)										$ 0.01	$ 0.00
Adjustment [Member] | Restatement of Net Profit (Loss) [Member] | Liberty Property Limited Partnership [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Interest and other income										$ 918	$ (69)
Total other income (expense)										918	(69)
Income before gain on property dispositions, income taxes and equity in earnings of unconsolidated joint ventures										918	(69)
Income taxes										560	377
Income from continuing operations										1,478	308
Net income										1,478	308
Income available to common shareholders										1,478	308
Other comprehensive (loss) income - foreign currency translation										(1,107)	(1,256)
Other comprehensive loss										(1,107)	(1,256)
Total comprehensive income										$ 371	$ (948)
Income from continuing operations (USD per share/unit)										$ 0.01	$ 0.00
Income per common share - basic (USD per share/unit)										$ 0.01	$ 0.00
Net income allocated to general partners										$ 1,444	$ 301
Net income allocated to limited partners										$ 34	$ 7
Common Stock [Member] | Restatement of Net Profit (Loss) [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income per common share - diluted (USD per share/unit)										$ 1.61	$ 1.16
Common Stock [Member] | Restatement of Net Profit (Loss) [Member] | Liberty Property Limited Partnership [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income per common share - diluted (USD per share/unit)										1.61	1.48
Common Stock [Member] | Previously Reported [Member] | Restatement of Net Profit (Loss) [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income per common share - diluted (USD per share/unit)										1.60	1.15
Common Stock [Member] | Previously Reported [Member] | Restatement of Net Profit (Loss) [Member] | Liberty Property Limited Partnership [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income per common share - diluted (USD per share/unit)										1.60	1.47
Common Stock [Member] | Adjustment [Member] | Restatement of Net Profit (Loss) [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income per common share - diluted (USD per share/unit)										0.01	0.01
Common Stock [Member] | Adjustment [Member] | Restatement of Net Profit (Loss) [Member] | Liberty Property Limited Partnership [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income per common share - diluted (USD per share/unit)										0.01	0.01
Common Units [Member] | Restatement of Net Profit (Loss) [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income per common share - diluted (USD per share/unit)										1.61	1.48
Common Units [Member] | Restatement of Net Profit (Loss) [Member] | Liberty Property Limited Partnership [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income per common share - diluted (USD per share/unit)										1.61	1.16
Common Units [Member] | Previously Reported [Member] | Restatement of Net Profit (Loss) [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income per common share - diluted (USD per share/unit)										1.60	1.47
Common Units [Member] | Previously Reported [Member] | Restatement of Net Profit (Loss) [Member] | Liberty Property Limited Partnership [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income per common share - diluted (USD per share/unit)										1.60	1.15
Common Units [Member] | Adjustment [Member] | Restatement of Net Profit (Loss) [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income per common share - diluted (USD per share/unit)										0.01	0.01
Common Units [Member] | Adjustment [Member] | Restatement of Net Profit (Loss) [Member] | Liberty Property Limited Partnership [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Income per common share - diluted (USD per share/unit)										$ 0.01	$ 0.01