Noncontrolling Interests - Operating Partnership (Details) $ / shares in Units, $ in Billions		3 Months Ended	12 Months Ended
	Dec. 12, 2012 shares	Mar. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 shares
Noncontrolling Interests - Operating Partnership
Series A Cumulative Preferred Stock, dividend rate (as a percent)		7.25%	7.25%
Operating partnership
Noncontrolling Interests - Operating Partnership
Conversion ratio for common operating partnership units		1
Preferred Operating Partnership units issued to CoreSite Realty Corporation (in shares)	4,600,000
Series A Cumulative Preferred Stock, dividend rate (as a percent)	7.25%
Number of Operating Partnership Units (in shares)		47,615,697	47,227,915
Percentage of Total		70.90%
Percentage of Total		29.10%
Percentage of Total		100.00%	100.00%
Shares of common stock issued related to employee compensation arrangements		387,782
Quarterly distributions will receive by holders of operating partnership units (in dollars per unit) | $ / shares		$ 0.80
Operating partnership | Coresite Realty Corporation
Noncontrolling Interests - Operating Partnership
Number of Operating Partnership Units (in shares)		33,764,350	33,376,568
Percentage of Total		70.90%	70.70%
Operating partnership | Noncontrolling Interests
Noncontrolling Interests - Operating Partnership
Number of Operating Partnership Units (in shares)		13,851,347	13,851,347
Percentage of Total		29.10%	29.30%
Redemption value of the noncontrolling interests | $		$ 1.2
Closing price of the Company's stock (in dollars per share) | $ / shares		$ 90.00