Related Party Transactions (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Related Party Transaction [Line Items]
Related party expenses	$ 2,966	$ 2,600	$ 5,531	$ 4,759
Base management fees incurred but not yet paid	2,966		2,966		2,628
Limited Liability Company [Member]
Related Party Transaction [Line Items]
Rate of management fees			1.50%
Period of termination			180 days
Period to be considered, for average annual base management fee			3
Limited Liability Company [Member] \| Management Fees [Member]
Related Party Transaction [Line Items]
Related party expenses	2,966	2,600	5,531	4,759
Base management fees incurred but not yet paid	2,966		2,966		2,628
Limited Liability Company [Member] \| Reimbursements [Member]
Related Party Transaction [Line Items]
Related party expenses	$ 185	$ 108	$ 292	$ 334