Amounts Incurred for Management Fee and Reimbursable Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Related Party Transaction [Line Items]
Management fee	$ 4,037	$ 4,122	$ 12,215	$ 12,420
Share-based compensation	966	890	3,045	2,592
Management Fees
Related Party Transaction [Line Items]
Management fee	4,037	4,122	12,215	12,420
Reimbursable expenses	1,124	715	3,681	2,403
Total	5,161	4,837	15,896	14,823
Share-based compensation	$ 966	$ 890	$ 3,045	$ 2,592