Organization - Additional Information (Detail) - USD ($)	Aug. 14, 2013	Jul. 17, 2013	May. 20, 2013
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of shares sold by the Company under follow-on offering	$ 0		$ 0
Investor [Member] | Common Stock [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Follow-on offering of common stock		8,000,000	9,974,985
Offering price, per share	$ 70.00	$ 70.00	$ 50.00
Investor [Member] | Over-Allotment Option [Member] | Common Stock [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Follow-on offering of common stock	1,200,000		1,301,085