Summary of Business and Significant Accounting Policies - Additional Information (Detail) (Class A common stock [Member], USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	6 Months Ended
	Mar. 31, 2014	Jul. 31, 2014
Class A common stock [Member]
Subsidiary Sale Of Stock [Line Items]
Shares issued in follow-on offering	13,800,000
Shares sold to underwriters under over-allotment option	1,800,000
Shares sold and issued by the Company	1,390,000
Shares sold by certain selling shareholders	12,410,000
Offering price per share	$ 26.35
Net proceeds from initial public offering, after deducting underwriting discounts and commissions	$ 35.3
Estimated offering costs	0.8
Net cash proceeds from offering		$ 34.5