Supplemental Cash Flow Information - Components of Change in Other Assets and Liabilities Net (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Supplemental Cash Flow Elements [Abstract]
Other current and noncurrent assets	$ (18,777)	$ (32,332)
Accrued salaries, benefits and payroll taxes	1,661	(7,892)
Accrued insurance and other taxes	(3,344)	(134)
Accrued income taxes	39,122	28,047
Accrued pension, postretirement and postemployment benefits	10,685	11,521
Other current and noncurrent liabilities	(23,732)	30,740
Change in other assets and liabilities, net	$ 5,615	$ 29,950