Organization and Significant Accounting Policies - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified	1 Months Ended	3 Months Ended
	Jan. 30, 2013	Mar. 31, 2013
Accounting Policies [Line Items]
Number of shares issued under initial public offering	11.6
Proceed from issuance of initial public offering	$ 233,300,000	$ 234,944,000
Payment of initial public offering costs	$ 1,600,000