Stock Incentive Plans - Summary of Activity of Stock Incentive and Equity Plans (Detail) (USD $)	1 Months Ended				2 Months Ended		3 Months Ended	7 Months Ended		12 Months Ended
	Sep. 30, 2014	Oct. 31, 2013	Jul. 31, 2012	Jan. 31, 2012	Oct. 31, 2012	May 31, 2012	Dec. 31, 2014	Jul. 31, 2014	Jul. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Shares available for grant
Shares available for grant, Beginning balance				2,259,999				2,240,103	2,200,604	2,240,103	2,200,604	2,259,999
Shares available for grant, Granted										(706,056)	(216,913)	(106,395)
Shares available for grant, Exercised/issued										0	0	0
Shares available for grant, Canceled/forfeited										238,482	256,412	47,000
Shares available for grant, Ending balance							1,772,529			1,772,529	2,240,103	2,200,604
Number of options outstanding
Number of options outstanding, Beginning balance				2,093,108				1,926,070	2,117,110	1,926,070	2,117,110	2,093,108
Number of options outstanding, Granted	300,000	14,450	7,000	8,500	36,800	36,750	235,650	39,300	82,815	574,950	97,265	89,050
Number of options outstanding, Exercised/issued										(47,654)	(27,930)	(17,885)
Number of options outstanding, Canceled/forfeited										(215,080)	(260,375)	(47,163)
Number of options outstanding, Ending balance							2,238,286			2,238,286	1,926,070	2,117,110
Weighted - average option exercise price
Weighted - average option exercise price, Beginning balance				$ 13.45				$ 12.46	$ 13.32	$ 12.46	$ 13.32	$ 13.45
Weighted - average option exercise price, Granted										$ 5.04	$ 8.43	$ 9.72
Weighted - average option exercise price, Exercised/issued										$ 5.37	$ 5.02	$ 4.01
Weighted - average option exercise price, Canceled/forfeited										$ 16.72	$ 18.31	$ 15.13
Weighted - average option exercise price, Ending balance							$ 10.31			$ 10.31	$ 12.46	$ 13.32
Number of restricted stock shares issued
Number of restricted stock shares issued, Beginning balance				42,587				133,639	59,932	133,639	59,932	42,587
Number of restricted stock shares issued, Granted										27,925	73,707	17,345
Number of restricted stock shares issued, Exercised/issued										0	0	0
Number of restricted stock shares issued, Canceled/forfeited										(20,911)
Number of restricted stock shares issued, Ending balance							140,653			140,653	133,639	59,932
Restricted Stock Units [Member]
Number of restricted stock units outstanding
Number of restricted stock units outstanding, Beginning balance								45,941		45,941
Number of restricted stock units outstanding, Granted										103,181	45,941
Number of restricted stock units outstanding, Exercised/issued										(10,525)
Number of restricted stock units outstanding, Canceled/forfeited										(3,866)
Number of restricted stock units outstanding, Ending balance							134,731			134,731	45,941