Other Expenses - Schedule of General and Administrative Expenses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Professional services	$ 933	$ 828	$ 2,811	$ 2,474
Operating and other costs	489	305	1,424	1,695
Subtotal	1,422	1,133	4,235	4,169
Non-cash and CT Legacy Portfolio compensation expenses
Restricted class A common stock earned	5,819	4,855	17,496	14,190
Subtotal	5,944	6,241	17,809	16,690
General and administrative expenses	7,419	7,414	22,219	20,990
Other expenses	53	40	175	131
General and Administrative Expense [Member]
Non-cash and CT Legacy Portfolio compensation expenses
Director stock-based compensation	125	94	313	282
Manager [Member]
Non-cash and CT Legacy Portfolio compensation expenses
Management incentive awards plan	3,700	4,200	11,900	14,800
General and administrative expenses	$ 7,366	7,374	$ 22,044	20,859
CT Legacy Partners [Member]
Non-cash and CT Legacy Portfolio compensation expenses
Management incentive awards plan		354		1,112
CT Opportunity Partners I, LP [Member]
Non-cash and CT Legacy Portfolio compensation expenses
Management incentive awards plan		$ 938		$ 1,106