Commitments and Contingencies - Changes in Accrued Environmental Remediation and Related Costs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]
Balance at the beginning of the year	$ 110,015	$ 113,636	$ 48,006
Additions charged to expense, net	4,370	6,485	68,929
Payments, net	(1,252)	(10,106)	(3,299)
Balance at the end of the year	113,133	110,015	113,636
Amounts recognized in the Condensed Consolidated Balance Sheet at the end of the period:
Current liability				$ 8,668	$ 6,984	$ 4,859
Noncurrent liability				104,465	103,031	108,777
Balance at the end of the year	$ 110,015	$ 113,636	$ 48,006	$ 113,133	$ 110,015	$ 113,636