Equity-Based Compensation - Employee Equity-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense	$ 469	$ 1,733	$ 2,858	$ 4,775
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense	794	595	1,975	1,599
Performance shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense	(682)	499	(164)	1,409
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense	$ 357	$ 639	$ 1,047	$ 1,767