Items Accounting for Differences between Income Taxes Computed at Federal Statutory Rate and Provision Recorded for Income Taxes (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Statutory Federal Tax Rate [Line Items]
Federal statutory rate	35.00%	35.00%	35.00%
Effect of:
Impact of foreign tax differential	31.50%	(8.40%)	(12.70%)
State taxes, net of federal benefits	0.20%	1.50%	1.50%
Tax credits	(4.40%)	(3.20%)	(1.10%)
Nondeductible stock-based compensation	11.10%	4.10%	1.60%
Other, net	5.20%	2.20%	(0.80%)
Total	78.60%	31.20%	23.50%