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Fair Value of Options Granted Estimated using the Black-Scholes Option-Pricing Model with Weighted-Average Assumptions (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2011 Year	Jun. 30, 2010 Year	Jun. 30, 2011 Year	Jun. 30, 2010 Year
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life (years)	5.50	5.50	5.50	5.63
Interest rate	1.60%	2.00%	1.60%	2.30%
Volatility	50.80%	51.80%	50.80%	51.70%
Dividend yield	0.00%	0.00%	0.00%	0.00%

The period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior.

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