Indebtedness - Activity (Details) (USD $)	12 Months Ended											0 Months Ended	3 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, 2012 Senior Notes [Member] 3.375% senior note [Member]	Dec. 31, 2012 Senior Notes [Member] 4.125% Senior Notes [Member]	Dec. 31, 2012 Senior Notes [Member] Unsecured Debt [Member] 6.375% Senior Notes [Member]	Dec. 31, 2011 Senior Notes [Member] Unsecured Debt [Member] 7.25% Senior Notes [Member]	Dec. 31, 2013 Mortgages [Member]	Dec. 31, 2012 Mortgages [Member] 4.84% Mortgage Loan [Member]	Dec. 31, 2013 Mortgages [Member] 4.84% Mortgage Loan [Member]	Oct. 08, 2013 Cabot Industrial Value Fund III [Member] Mortgages [Member]	Dec. 31, 2013 Cabot Industrial Value Fund III [Member] Mortgages [Member]
Debt Instrument [Line Items]
Proceeds from unsecured notes	$ 448,646,000	$ 700,000,000	$ 0	$ 450,000,000
Assumption of mortgage debt from acquisition												229,800,000
Debt Instrument, Borrowing Capacity, Amount										45,000,000
Repayments of Senior Debt							230,100,000	246,500,000
Debt Instrument, Interest Rate, Stated Percentage				4.40%	3.375%	4.125%	6.375%	7.25%
Debt Instrument, Maturity Date, Description				2024	2023	2022	August 2012			2033
Debt Instrument, Maturity Date Range, Start									Jan. 01, 2014				Jan. 01, 2018
Debt Instrument, Maturity Date Range, End									Dec. 31, 2033				Dec. 31, 2021
Debt, Weighted Average Interest Rate	5.10%	5.30%	5.80%							4.84%			5.85%
Mortgage Loans	545,306,000	302,855,000									44,500,000
Debt Instrument, Face Amount				$ 450,000,000	$ 300,000,000	$ 400,000,000
Term of Debt							10 years