Stockholders' Equity (Stock Option Activity) (Detail)	3 Months Ended
	Mar. 31, 2016 $ / shares shares
Number of options
Number of options, outstanding at December 31, 2015 (in shares) | shares	5,126,000
Number of options, Granted (in shares) | shares	1,960,000
Number of options, Exercised (in shares) | shares	(43,000)
Number of options, Canceled/forfeited/expired (in shares) | shares	(419,000)
Number of options, outstanding at March 31, 2016 (in shares) | shares	6,624,083.000
Weighted average exercise price
Weighted average exercise price, Options outstanding at December 31, 2015 (in dollars per share) | $ / shares	$ 8.91
Weighted average exercise price, Granted (in dollars per share) | $ / shares	6.75
Weighted average exercise price, Exercised (in dollars per share) | $ / shares	4.83
Weighted average exercise price, Canceled/forfeited/expired (in dollars per share) | $ / shares	10.61
Weighted average exercise price, Options outstanding at March 31, 2016 (in dollars per share) | $ / shares	$ 8.19