Restructuring, Asset Impairment, and Transition Expenses - Reconciliation of Accrued Restructuring Costs (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Restructuring Reserve [Roll Forward]
Beginning Balance			$ 1,971
Restructuring expense incurred	$ 1,198	$ 1,641	3,096	$ 3,194
Cash payments			(3,631)
Ending Balance	$ 1,436		$ 1,436