Warrants Outstanding and Exercisable (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Class of Warrant or Right [Line Items]
Warrants Outstanding, Number Outstanding | shares	183
Warrants Outstanding, Weighted Average Remaining Contractual Life (Years)	4 years 7 months 6 days
Warrants Outstanding, Weighted Average Exercise Price (per share) | $ / shares	$ 52.24
Warrants Exercisable, Number Exercisable | shares	63
Warrants Exercisable, Weighted Average Exercise Price (per share) | $ / shares	$ 114.28
Warrants 2014 [Member]
Class of Warrant or Right [Line Items]
Warrants Outstanding, Number Outstanding | shares	1
Warrants Outstanding, Weighted Average Remaining Contractual Life (Years)	1 month 6 days
Warrants Outstanding, Weighted Average Exercise Price (per share) | $ / shares	$ 948.00
Warrants Exercisable, Number Exercisable | shares	1
Warrants Exercisable, Weighted Average Exercise Price (per share) | $ / shares	$ 948.00
Warrants 2016 [Member]
Class of Warrant or Right [Line Items]
Warrants Outstanding, Number Outstanding | shares	6
Warrants Outstanding, Weighted Average Remaining Contractual Life (Years)	3 years
Warrants Outstanding, Weighted Average Exercise Price (per share) | $ / shares	$ 466.26
Warrants Exercisable, Number Exercisable | shares	6
Warrants Exercisable, Weighted Average Exercise Price (per share) | $ / shares	$ 466.26
Warrants 2017 [Member]
Class of Warrant or Right [Line Items]
Warrants Outstanding, Number Outstanding | shares	56
Warrants Outstanding, Weighted Average Remaining Contractual Life (Years)	3 years 8 months 12 days
Warrants Outstanding, Weighted Average Exercise Price (per share) | $ / shares	$ 55.63
Warrants Exercisable, Number Exercisable | shares	56
Warrants Exercisable, Weighted Average Exercise Price (per share) | $ / shares	$ 55.63
Warrants 2018 [Member]
Class of Warrant or Right [Line Items]
Warrants Outstanding, Number Outstanding | shares	120
Warrants Outstanding, Weighted Average Remaining Contractual Life (Years)	5 years 2 months 12 days
Warrants Outstanding, Weighted Average Exercise Price (per share) | $ / shares	$ 19.20
Warrants Exercisable, Number Exercisable | shares	0
Warrants Exercisable, Weighted Average Exercise Price (per share) | $ / shares	$ 0