Business Combination Business Combination (Details) (USD $)	12 Months Ended					0 Months Ended	12 Months Ended		0 Months Ended		12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Senior Notes [Member] 4.40% senior unsecured note [Member]	Dec. 31, 2013 Common Shares Equity Offering [Member] Common Stock [Member]	Oct. 08, 2013 Cabot Industrial Value Fund III [Member] sqft	Dec. 31, 2013 Cabot Industrial Value Fund III [Member]	Dec. 31, 2012 Cabot Industrial Value Fund III [Member]	Oct. 08, 2013 Cabot Industrial Value Fund III [Member] Mortgages [Member]	Dec. 31, 2013 Cabot Industrial Value Fund III [Member] Senior Notes [Member] 4.40% senior unsecured note [Member]	Dec. 31, 2013 Cabot Industrial Value Fund III [Member] Leases, Acquired-in-Place [Member]	Oct. 08, 2013 Industrial Property [Member] Cabot Industrial Value Fund III [Member] properties
Business Combination, Description [Abstract]
Name of Acquired Entity							Cabot Industrial Fund III Operating Partnership, L.P.
Percentage of Voting Interests Acquired						100.00%
Number of Real Estate Properties												177
Area of Real Estate Property						23,000,000
Business Acquisition, Date of Acquisition [Abstract]
Date of Acquisition							Oct. 08, 2013
Business Combination, Consideration Transferred [Abstract]
Assumption of mortgage debt from acquisition									$ 229,800,000
Total purchase price of acquisition						1,469,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets [Abstract]
Land and land improvements						247,393,000
Building and improvements						1,152,717,000
Operating real estate						1,400,110,000
Intangible - in-place leases/market rent						97,396,000
Other assets						4,953,000
Total assets						1,502,459,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities [Abstract]
Mortgage loans						243,230,000	243,230,000
Other liabilities						32,958,000
Intangible market rent						5,737,000
Total liabilities						281,925,000
Net assets acquired						1,220,534,000
Acquired Finite-Lived Intangible Assets [Abstract]
Weighted average useful life of acquired of in-place lease intangible assets											4 years 5 months 0 days
Business Combination, Costs Incurred or to be Incurred [Abstract]
Acquisition costs							7,600,000
Financing fees							4,200,000
Deferred financing costs	36,882,000	32,023,000					2,000,000			3,900,000
Mortgage loans acquired before fair value adjustment							229,800,000
Proceeds from unsecured notes	448,646,000	700,000,000	0	450,000,000
Stock issuance costs							35,300,000
Number of common shares issued					24,200,000
Business Acquisition, Pro Forma Information [Abstract]
Total operating revenue							750,896,000	692,583,000
Net income available to common shareholders							211,601,000	134,295,000
Operating revenue	645,930,000	560,279,000	533,699,000				31,400,000
Operating Income (Loss)	$ 203,047,000	$ 189,942,000	$ 190,995,000				$ 22,000,000