Property, Plant and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property Plant and Equipment Useful Life and Values [Abstract]
Depreciation	$ 46,599	$ 36,456	$ 30,462
Capitalized computer software amortization expense	21,800	17,700	$ 11,600
Unamortized computer software costs	$ 75,800	$ 60,200