Warrants Outstanding and Exercisable (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Class of Warrant or Right [Line Items]
Warrants Outstanding, Number Outstanding | shares	5,951
Warrants Outstanding, Weighted Average Remaining Contractual Life (Years)	3 years 7 months 6 days
Warrants Outstanding, Weighted Average Exercise Price (per share) | $ / shares	$ 3.43
Warrants Exercisable, Number Exercisable | shares	2,760
Warrants Exercisable, Weighted Average Exercise Price (per share) | $ / shares	$ 4.73
Warrants 2013 [Member]
Class of Warrant or Right [Line Items]
Warrants Outstanding, Number Outstanding | shares	10
Warrants Outstanding, Weighted Average Remaining Contractual Life (Years)	1 year 3 months 18 days
Warrants Outstanding, Weighted Average Exercise Price (per share) | $ / shares	$ 0.90
Warrants Exercisable, Number Exercisable | shares	10
Warrants Exercisable, Weighted Average Exercise Price (per share) | $ / shares	$ 0.90
Warrants 2014 [Member]
Class of Warrant or Right [Line Items]
Warrants Outstanding, Number Outstanding | shares	2,750
Warrants Outstanding, Weighted Average Remaining Contractual Life (Years)	2 years 1 month 6 days
Warrants Outstanding, Weighted Average Exercise Price (per share) | $ / shares	$ 4.74
Warrants Exercisable, Number Exercisable | shares	2,750
Warrants Exercisable, Weighted Average Exercise Price (per share) | $ / shares	$ 4.74
Warrants 2015 [Member]
Class of Warrant or Right [Line Items]
Warrants Outstanding, Number Outstanding | shares	0
Warrants Outstanding, Weighted Average Remaining Contractual Life (Years)	0 years
Warrants Outstanding, Weighted Average Exercise Price (per share) | $ / shares	$ 0
Warrants Exercisable, Number Exercisable | shares	0
Warrants Exercisable, Weighted Average Exercise Price (per share) | $ / shares	$ 0
Warrants 2016 [Member]
Class of Warrant or Right [Line Items]
Warrants Outstanding, Number Outstanding | shares	3,191
Warrants Outstanding, Weighted Average Remaining Contractual Life (Years)	5 years
Warrants Outstanding, Weighted Average Exercise Price (per share) | $ / shares	$ 2.31
Warrants Exercisable, Number Exercisable | shares	0
Warrants Exercisable, Weighted Average Exercise Price (per share) | $ / shares	$ 0