Stock-Based Compensation - Common Stock Option and Restricted Stock Award Activity (Detail) (USD $)	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Average Exercise Price Per share, End of year	$ 2.71
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Available For Grant, Authorized	706,950
Shares Available For Grant, Options Granted	(959,198)
Shares Available For Grant, Options assumed in Merger	(15,000)
Shares Available For Grant, Restricted Stock Granted	(19,088)
Shares Available For Grant, Restricted Stock Vested	0
Shares Available for Grant, End of year	1,000,311	1,286,647
Number of Shares, Authorized	0
Number of Shares, Options Granted	959,198
Number of Shares, Options assumed in Merger	15,000
Number of Shares, Restricted Stock Granted	19,088
Number of Shares, Restricted Stock Vested	(337,216)
Number of Shares, End of Year	2,267,918	1,611,848
Number of Shares, Total vested and expected to vest shares (options)	2,267,918
Weighted Average Exercise Price Per Share, Authorized	$ 0
Weighted Average Exercise Price Per Share, Options Granted	$ 3.12
Weighted Average Exercise Price Per Share, Options assumed in Merger	$ 14.30
Weighted Average Exercise Price Per Share, Restricted Stock Granted	$ 3.04
Weighted Average Exercise Price Per Share, Restricted Stock Vested	$ 2.31
Weighted Average Exercise Price Per share, End of year	$ 2.71
Weighted Average Exercise Price Per Share, Total vested and expected to vest shares (options)	$ 2.71