Organization (Details)							0 Months Ended							0 Months Ended	12 Months Ended
	Dec. 31, 2013 sqft	Dec. 31, 2012 sqft	Dec. 31, 2013 Maximum	Dec. 31, 2013 Consolidated portfolio sqft property	Dec. 31, 2013 Wholly owned portfolio CBD property sqft	Dec. 31, 2013 Wholly owned portfolio Suburban property sqft property	Jul. 02, 2013 SIR	Dec. 31, 2013 SIR	Dec. 31, 2012 SIR	Dec. 31, 2013 GOV	Mar. 15, 2013 GOV	Dec. 31, 2012 GOV	Dec. 31, 2013 Australia Wholly owned portfolio property sqft	Mar. 12, 2012 SIR	Dec. 31, 2013 SIR	Dec. 31, 2012 SIR	Feb. 16, 2012 SIR sqft	Dec. 31, 2013 SIR Previously reported
Organization
Properties owned				125	38	87							11
Number of buildings				195	51	144							11
Property square feet	37,273,000	61,806,000		37,273,000	20,975,000	16,298,000							1,759,000				21,400,000
Equity method investments, ownership percentage			50.00%				56.00%	44.20%	56.00%	0.00%	18.20%	18.20%			44.20%
Ownership percentage prior to initial public offering														100.00%	100.00%
Issuance of shares, net (in shares)							10,500,000							9,200,000
Wholly owned subsidiary, common shares owned															22,000,000	22,000,000
Ownership percentage								44.20%								56.00%		56.00%
Equity investments, common shares owned							22,000,000	22,000,000			9,950,000				22,000,000