Income Taxes - Reconciliation of the Federal Statutory Rate (Detail)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax provision at federal statutory rate	21.00%	21.00%	35.00%
Increase (decrease) in tax resulting from:
State tax provision, net of federal benefit	8.30%	6.20%	4.00%
Foreign tax rate differential	0.40%	(0.20%)	(3.40%)
Stock option compensation deduction	(1.20%)	(1.10%)	0.10%
Withholding taxes	(3.50%)	2.10%	1.70%
Non-deductible expenses	(9.80%)	5.30%	1.80%
Change in valuation allowance	2.30%		3.90%
Foreign subsidiary income subject to U.S. tax	(7.40%)
Change in tax legislation	(0.012)	0.019	0.058
Audit settlements	(8.30%)		(4.00%)
Other, net	(0.30%)	(0.60%)	(0.20%)
Effective tax rate	0.30%	34.60%	44.70%