Equity Investment in Unconsolidated Subsidiary - Additional Information (Detail) - CT Opportunity Partners I, LP [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 31, 2011
Schedule of Equity Method Investments [Line Items]
Carried interest revenue, percentage of fund's profit	17.70%
Preferred return	9.00%
Return of capital to partners	100.00%
Promote income recognized		$ 3.2	$ 11.8
Percentage of carried interest distributions pool for employees				45.00%
Description of incentive management fee grants to employees vesting schedule	During the years ended December 31, 2016 and 2015, we recognized $1.6 million and $5.4 million, respectively, of expenses under the CTOPI incentive plan. Such amounts were recognized as a component of general and administrative expenses in our consolidated statements of operations.
CTOPI Incentive Plan [Member]
Schedule of Equity Method Investments [Line Items]
Recognized expenses for incentive plan		$ 1.6	$ 5.4