Overview and Basis of Presentation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Basis Of Presentation [Line Items]
Reserve stock split	1-for-2.75
Additional outstanding shares common stock	19,731,564
IPO [Member]
Basis Of Presentation [Line Items]
Common stock shares purchased	6,772,221
Public offering price	$ 18.00
Number of shares of common stock issued upon the exercise in full by the underwriters of their option to purchase additional shares at the public offering price	883,333
Net proceeds from the IPO	$ 111.1
Private Placement [Member]
Basis Of Presentation [Line Items]
Common stock shares purchased	708,333
Public offering price	$ 18.00
Celgene [Member]
Basis Of Presentation [Line Items]
Aggregate proceeds on IPO	$ 12.8