Summary of Significant Accounting Policies (Additional Information 1) (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Feb. 29, 2012	Feb. 08, 2012
Summary Of Significant Accounting Policies [Line Items]
Asset write off			$ 3,100
Impairment losses			0	$ 0	$ 0
Goodwill			181,738
Amortization of the deferred financing costs		$ 496	3,181	2,673
Written off unamortized debt cost	$ 500			900
Amortization of deferred leasing costs totaled			11,800	9,400	6,500
Deferred income		$ 7,900	16,991	10,531	7,900
Amortization of deferred revenue			6,000	4,700	4,700
Deferred leasing costs, net			16,434	16,469
Company recorded equity-based compensation expense net of repurchased awards and forfeits			7,000	4,200	2,000
Amount of the straight-line rent receivable on the balance sheets included in rents and other receivables			9,100	4,000
Unsecured Revolving Credit Facility [Member]
Summary Of Significant Accounting Policies [Line Items]
Amortization of the deferred financing costs			3,200	2,700	$ 2,800
Repayment of credit facility				75,000
Interest Rate Swap [Member]
Summary Of Significant Accounting Policies [Line Items]
Derivative liability			0	0
Derivative ineffectiveness				0
Interest Rate Swap [Member] | Cash Flow Hedging [Member]
Summary Of Significant Accounting Policies [Line Items]
Notional amount of derivative						$ 150,000	$ 150,000
Carpathia Hosting, Inc. [Member]
Summary Of Significant Accounting Policies [Line Items]
Goodwill	$ 173,237		$ 181,738
Princeton Facility [Member]
Summary Of Significant Accounting Policies [Line Items]
Deferred leasing costs, net				$ 2,800