Summary of Significant Accounting Policies - Additional Information 2 (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014 Subsidiary	Dec. 31, 2013
Summary Of Significant Accounting Policies [Line Items]
Aggregate allowance for doubtful accounts	$ 1,500,000	$ 900,000
Outstanding liabilities for the capital leases	$ 4,441,000	$ 2,538,000
Number of subsidiaries taxed as taxable REIT	1
Customer One [Member] | Rental Revenue [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of total revenue	8.00%
Customer Two [Member] | Rental Revenue [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of total revenue	5.00%
Other Customers [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of total accounts receivable	10.00%
Other Customers [Member] | Rental Revenue [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of total revenue	5.00%
Five Customers [Member] | Accounts Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of total revenue	5.00%
Five Customers [Member] | Accounts Receivable [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of total revenue	33.50%