Share-Based Compensation - Stock Option Valuation Assumptions Table (Detail) (Employee and Nonemployee Stock Options [Member])	12 Months Ended
	Dec. 31, 2011 Year	Dec. 31, 2010 Year	Dec. 31, 2009 Year
Employee and Nonemployee Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected option life-years	4.8	4.9	4.9
Volatility	42.00%	43.90%	46.30%
Risk-free interest rate	1.50%	2.00%	1.90%
Dividend yield	0.50%	0.70%	0.80%