Components of Prepaid Expenses and Other (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Prepaid Expenses [Line Items]
Prepaid expenses and other, current	$ 4,477	$ 2,635
Prepaid expenses and other, long-term	8,831	5,080
Totals	13,308	7,715
CRO services
Prepaid Expenses [Line Items]
Prepaid expenses and other, current	1,584	863
Prepaid expenses and other, long-term	5,302	1,509
Other clinical development
Prepaid Expenses [Line Items]
Prepaid expenses and other, current	2,463	1,089
Prepaid expenses and other, long-term	3,318	3,359
Insurance
Prepaid Expenses [Line Items]
Prepaid expenses and other, current	228	554
Prepaid expenses and other, long-term	159	142
Other
Prepaid Expenses [Line Items]
Prepaid expenses and other, current	202	129
Prepaid expenses and other, long-term	$ 52	$ 70