Fair Value of Each Award Estimated on Date of Grant Using Black-Scholes-Merton Option-Pricing Formula (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock Options
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Expected volatility, min		64.60%	56.20%
Expected volatility, max		69.40%	63.70%
Dividend yield, min		0.00%	0.00%
Dividend yield, max		0.00%	0.00%
Risk-free interest rate, min		0.87%	0.82%
Risk-free interest rate, max		1.54%	1.63%
Stock Options | Minimum
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Expected life		3 years 6 months	3 years 6 months
Stock Options | Maximum
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Expected life		4 years 7 months	4 years 7 months
Performance Based Restricted Stock Units (PBRSUs)
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Expected volatility, min	66.50%	52.60%
Expected volatility, max	97.70%	72.30%
Dividend yield, min	0.00%	0.00%
Dividend yield, max	0.00%	0.00%
Risk-free interest rate, min	1.00%	0.02%
Risk-free interest rate, max	1.31%	1.07%