Significant Components of Net Deferred Income Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred income tax assets
Inventory costs	$ 29,453	$ 63,756
Property, plant and equipment		2,789
Accrued employee benefits	34,472	41,246
Accrued operating expenses	24,904	42,544
Reserves	16,434	26,731
Investments	8,796	667
Loss carryforwards	91,832	67,645
Research and development and other credits	164,841	118,113
Capitalized research and development	83,224	177,594
Other	17,379	50,171
Total deferred income tax assets	471,335	591,256
Deferred income tax liabilities:
Property, plant and equipment	(571)
Other liabilities	(7,190)	(6,656)
Goodwill and intangible assets	(325,283)	(451,600)
Total deferred income tax liabilities	(333,044)	(458,256)
Net deferred income tax assets	138,291	133,000
Valuation allowance	(91,743)	(57,772)	$ (87,788)	$ (118,629)
Net deferred income tax assets	$ 46,548	$ 75,228