Organization - Additional Information (Detail) (USD $)	1 Months Ended		12 Months Ended		1 Months Ended
	Nov. 30, 2013	May 31, 2013	Dec. 31, 2013 Segment	Oct. 31, 2013	Nov. 30, 2013 Follow-on Offering	Oct. 31, 2013 Follow-on Offering	Nov. 30, 2013 Underwriters Overallotment Option	May 31, 2013 Underwriters Overallotment Option
Organization And Nature Of Business [Line Items]
Number of operating segment			1
Stock issued during the period		9,686,171				6,366,513	954,976	1,263,413
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			862,000
Proceeds from initial public offering, net of underwriters discount		125,800,000	251,865,000
Number of preferred stock converted into common stock		24,026,797	24,026,797
Stock Issued during period shares existing shareholder						1,908,803
Follow on offering price per share				$ 23.75
Proceeds from offering and over-allotment option, gross	120,800,000
Underwriting discounts and commissions, net					7,700,000
Proceeds from offering and over-allotment option, net	$ 119,900,000