Reconciliations Between Statutory Federal Income Tax Rate and Effective Rate (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Statutory Federal income tax rate	34.00%	34.00%	34.00%
Increase (Decrease) resulting from:
U.S. Taxes on foreign income, net of taxes paid credit		1.30%	1.00%
Change in valuation allowance	10.60%	5.30%	(1.90%)
Foreign, state and local tax, net of Federal benefit	0.80%	1.10%	1.60%
Nondeductible expenses	2.40%	2.40%	1.80%
Stock option compensation	(2.20%)		(0.10%)
Research and development credits	(4.60%)	(0.70%)	(0.90%)
Effect of different tax rates of foreign jurisdictions	(20.80%)	(15.00%)	(12.10%)
Undistributed profits of subsidiaries	5.80%	7.90%	2.40%
Tax reform items	29.10%
Other tax exempt income			(0.10%)
Tax effects of intercompany transfers	(5.00%)	(5.30%)
Other	(1.00%)	(0.30%)	0.30%
Effective rate	49.10%	30.70%	26.00%