Organization - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended
	May 31, 2013	Sep. 30, 2013 Segment
Organization And Nature Of Business [Line Items]
Number of operating segment		1
Common stock initial public offering	9,686,171
Public offering price of the shares sold	$ 14.50
Proceeds from initial public offering before offering costs	$ 131,000,000
Underwriting discounts and commissions	9,400,000
Offering expenses	5,200,000
Proceeds from initial public offering, net of underwriters discount	$ 125,800,000	$ 131,026,000
Number of preferred stock converted into common stock	24,026,797
Underwriters Overallotment Option
Organization And Nature Of Business [Line Items]
Common stock initial public offering	1,263,413