Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended	0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Sep. 03, 2013	Mar. 30, 2014
Accounting Policies [Line Items]
Accumulated deficit	$ (146,036,000)		$ (135,916,000)
Net Income Loss Attributable To Parent	(10,120,000)	(7,479,000)
Reverse stock split, ratio		0.2
Common stock, shares issued	64,478,085	48,855,255	63,182,806		244,276,923
Common stock, shares outstanding	64,478,085	48,855,255	63,182,806		244,276,923
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001
Impairment charges	$ 0		$ 0
Maximum [Member]
Accounting Policies [Line Items]
Amortization period	10 years
Merger Agreement [Member]
Accounting Policies [Line Items]
Exchange ratio				1.1533
Common stock, shares outstanding				12,350,000
Common stock, par value (in dollars per share)				$ 0.001
Amortization period				5 years