Variation of Provision for Income Taxes from Statutory U.S. Federal Income Tax Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income taxes computed at the statutory U.S. federal income tax rate	$ 83,884	$ 81,171	$ 88,512
State income taxes, net of federal tax benefit	4,529	4,264	4,903
Tax liabilities required (no longer required)	1,254	(408)	2,342
Valuation allowance	4,636	474	1,441
Manufacturing exemption	(5,143)	(3,613)	(7,849)
Tax credit refunds, net	(2,797)	(2,676)	(2,325)
Foreign earnings taxed at other than 35%	(3,840)	(2,334)	(6,383)
Deferred tax rate changes	(114,163)	(371)	163
Other	1,662	2,059	(331)
(Benefit) Provision for income taxes	$ (29,978)	$ 78,566	$ 80,473
Effective tax rate	(12.50%)	33.90%	31.80%