Schedule Of Noncash Investing and Financing Activities (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Supplemental Cash Flow Elements [Abstract]
Accrued liabilities for purchases of property, plant and equipment	$ 35,639	$ 34,666
Acquisition of assets through capital lease	$ 192	$ 149