Equity-Based Compensation - Summary of Equity-Based Compensation Expense, the Corresponding Tax Benefit and Net Equity-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity-based compensation expense	$ 1,059	$ 1,626	$ 1,317
Tax benefit	312	516	413
Net equity-based compensation expense	$ 747	$ 1,110	$ 904