Subsequent Event - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	6 Months Ended
	Jul. 05, 2013	Jun. 30, 2013
Mid Cap [Member]
Subsequent Event [Line Items]
Unregistered shares of common stock		357,356
Warrant exercise price		4.20
Subsequent Event [Member]
Subsequent Event [Line Items]
Secured loan facility	$ 20
Net proceeds in aggregate amount	19.9
Unregistered shares of common stock		357,356
Warrant exercise price		4.20
Days of volume-weighted average share price		20-day volume-weighted average share price of the Common Stock prior to the closing of the Loan
Warrant exercisable term		5 years
Term of loan		36 months
Period for payment of interest		6 months
Interest rate		8.45%
LIBOR floor Rate		0.50%
Final payment fee Rate		3.50%
Closing fee		0.50%
Loan amount prepaid in the first year of the Loan		5.00%
Loan amount prepaid in each year thereafter		3.00%
Prepayment of principal amount of the Loan rate		50.00%
Cash prepayment fee of principal amount of Loan		2.00%
Percentage of prepayment amount to purchase shares of Common Stock		2.00%
Subsequent Event [Member] | TTY License and Supply Agreement [Member]
Subsequent Event [Line Items]
The approval in Taiwan results in a milestone payment		0.3
Subsequent Event [Member] | Mid Cap [Member]
Subsequent Event [Line Items]
Secured loan facility	20
Net proceeds in aggregate amount	$ 19.9
Notice Period		10 days
Rate of interest Applicable to obligations		4.00%