Summary of Changes to Restructuring Accrual (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Balance at December 31, 2016	$ 30,129
Restructuring charges	13,477	$ 96,300
Cash payments / adjustments	(18,862)
Non-cash expense	(1,453)
Balance at June 30, 2017	23,291	30,129
Employee severance & termination benefits
Restructuring Cost and Reserve [Line Items]
Balance at December 31, 2016	27,886
Restructuring charges	7,464
Cash payments / adjustments	(16,410)
Balance at June 30, 2017	18,940	27,886
Contractual obligations and other
Restructuring Cost and Reserve [Line Items]
Balance at December 31, 2016	2,243
Restructuring charges	4,560
Cash payments / adjustments	(2,452)
Balance at June 30, 2017	4,351	$ 2,243
Write-off of property, plant and equipment
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,453
Non-cash expense	$ (1,453)