Summary of Significant Accounting Policies (Additional Information 1) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Jun. 16, 2015	Dec. 31, 2014	Feb. 29, 2012	Feb. 08, 2012
Summary Of Significant Accounting Policies [Line Items]
Impairment losses	$ 0	$ 0	$ 0	$ 0
Goodwill	173,237		173,237
Amortization of the deferred financing costs			1,585	1,314
Amortization of deferred leasing costs totaled	2,800	2,100	5,500	4,200
Deferred income	19,557		19,557			$ 10,531
Amortization of deferred revenue	1,400	1,200	2,700	2,400
Company recorded equity-based compensation expense net of repurchased awards and forfeits	1,800	1,100	3,100	2,000
Amount of the straight-line rent receivable on the balance sheets included in rents and other receivables	5,800		5,800			$ 4,000
Unsecured Revolving Credit Facility [Member]
Summary Of Significant Accounting Policies [Line Items]
Amortization of the deferred financing costs	800	600
Interest Rate Swap [Member]
Summary Of Significant Accounting Policies [Line Items]
Notional amount of derivative	0		0
Derivative ineffectiveness		$ 0		$ 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	$ 173,000		$ 173,000		$ 173,237