Stock Incentive Plans - Summary of Activity of Stock Incentive and Equity Plans (Detail) - $ / shares	1 Months Ended		3 Months Ended	4 Months Ended	5 Months Ended	7 Months Ended		12 Months Ended
	Sep. 30, 2014	Oct. 31, 2013	Dec. 31, 2014	Dec. 31, 2015	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Shares available for grant
Shares available for grant, Beginning balance						2,240,103	2,200,604	1,772,529	2,240,103	2,200,604
Shares available for grant, Granted								(1,457,826)	(706,056)	(216,913)
Shares available for grant, Exercised								0	0	0
Shares available for grant, Canceled/forfeited								417,567	238,482	256,412
Shares available for grant, Ending balance			1,772,529	732,270				732,270	1,772,529	2,240,103
Number of options outstanding
Number of options outstanding, Beginning balance						1,926,070	2,117,110	2,238,286	1,926,070	2,117,110
Number of options outstanding, Granted	300,000	14,450	235,650	900,084	92,600	39,300	82,815	992,684	574,950	97,265
Number of options outstanding, Exercised								(5,692)	(47,654)	(27,930)
Number of options outstanding, Canceled/forfeited								(373,710)	(215,080)	(260,375)
Number of options outstanding, Ending balance			2,238,286	2,851,568				2,851,568	2,238,286	1,926,070
Weighted - average option exercise price
Weighted - average option exercise price, Beginning balance						$ 12.46	$ 13.32	$ 10.31	$ 12.46	$ 13.32
Weighted - average option exercise price, Granted								1.40	5.04	8.43
Weighted - average option exercise price, Exercised								0.78	5.37	5.02
Weighted - average option exercise price, Canceled/forfeited								10.02	16.72	18.31
Weighted - average option exercise price, Ending balance			$ 10.31	$ 7.07				$ 7.07	$ 10.31	$ 12.46
Number of restricted stock and board shares issued
Number of restricted stock shares issued, Beginning balance						133,639	59,932	140,653	133,639	59,932
Number of restricted stock shares issued, Granted								60,802	27,925	73,707
Number of restricted stock shares issued, Exercised								0	0	0
Number of restricted stock shares issued, Canceled/forfeited									(20,911)
Number of restricted stock shares issued, Ending balance			140,653	201,455				201,455	140,653	133,639
Restricted Stock Units [Member]
Number of restricted stock units outstanding
Number of restricted stock units outstanding, Beginning balance						45,941		134,731	45,941
Number of restricted stock units outstanding, Granted								404,340	103,181	45,941
Number of restricted stock units outstanding, Exercised								(29,432)	(10,525)
Number of restricted stock units outstanding, Canceled/forfeited								(55,618)	(3,866)
Number of restricted stock units outstanding, Ending balance			134,731	454,021				454,021	134,731	45,941