Summary of Significant Accounting Policies - Additional Information (Detail)			6 Months Ended	12 Months Ended
	Mar. 31, 2014 $ / shares shares	Sep. 03, 2013 $ / shares shares	Jun. 30, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Mar. 30, 2014 shares
Accounting Policies [Line Items]
Reverse stock split, ratio	0.2
Common stock, shares issued	48,855,255		82,481,722	63,182,806	244,276,923
Common stock, shares outstanding	48,855,255		82,481,722	63,182,806	244,276,923
Common stock, par value (in dollars per share) | $ / shares	$ 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
Reverse stock split, ratio		1.1533
Common stock, shares outstanding		12,350,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.001
Amortization period		5 years