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Organization And Operations Of The Company (Details) (USD $)	12 Months Ended		1 Months Ended
	Dec. 31, 2010	Dec. 31, 2011	Jun. 22, 2010 OAS Holding Company LLC [Member]	Jun. 22, 2010 IPO [Member]
Organization And Operations Of The Company [Line Items]
Sale of common stock	92,240,345	92,483,393	17,930,000	30,370,000
Sale of common stock price per share	$ 0.01	$ 0.01	$ 14	$ 14.00
Underwriting discounts and commissions				$ 25,500,000
Proceeds from issuance of initial public offering	$ 399,669,000		$ 236,000,000

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Fees and commissions paid for the securities underwriting activities related to the initial public offering.

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Face amount or stated value of common stock per share; generally not indicative of the fair market value per share.

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