Share-Based and Long-Term Incentive Compensation - Share Based Compensation Expense (Income) Included in Operating Expense (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]
Share based and Long Term Incentive Compensation	$ 424	$ 1,024	$ 2,767	$ 2,980
General and administrative expense
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share based and Long Term Incentive Compensation	361	672	1,847	2,516
Other Operating Expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share based and Long Term Incentive Compensation	$ 63	$ 352	$ 920	$ 464