Employee Share-Based Compensation Plans - Summary Weighted-average Fair Value of the Shares Issued Under the ESPP Plans (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	47.50%	52.40%	53.80%
Expected dividend yield
Expected life (in years)	3 years 9 months	3 years 10 months 10 days	3 years 7 months 10 days
Risk-free interest rate	0.40%	0.40%	1.10%
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	42.70%	52.50%	53.40%
Expected dividend yield
Expected life (in years)	3 months	3 months	3 months
Risk-free interest rate	0.10%	0.10%	0.10%