Initial Public Offering and Tax Receivable Agreement (Details) (USD $)	0 Months Ended	3 Months Ended				0 Months Ended	9 Months Ended
	Jun. 02, 2011 debtors	Jun. 30, 2012	Sep. 30, 2012	Dec. 31, 2011	Jun. 02, 2011 Common Class B [Member]	Jun. 02, 2011 Initial Public Offering [Member]	Sep. 30, 2011 Initial Public Offering [Member]	Sep. 30, 2011 Initial Public Offering [Member] Repayments to Unaffiliated Debt Holders [Member]
Initial Public Offering and Tax Receivable Agreement [Abstract]
Gross Proceeds from initial public offering	$ 187,200,000
Common stock price at IPO (in dollars per share)	$ 12.00
Proceeds from IPO, after underwriter commissions	176,900,000
Proceeds from IPO, after paying debt and direct issuance costs	150,000,000
Debts paid from IPO proceeds	20,600,000
Number of unaffiliated debt holders paid with IPO proceeds (in debtors)	3
Direct IPO costs	5,900,000
Debt exchanged for common stock	279,200,000
Unpaid dividends exchanged for common stock	81,700,000
Common shares exchanged for forgiveness of debt and unpaid dividends (in shares)	30,079,420
Interest expense reduction from IPO transactions	400,000
Percentage of cash savings from pre-IPO NOLs due to pre-IPO stockholders	90.00%
Cash payment including interest to pre-IPO stockholders pursuant to tax receivable agreement		27,200,000
Interest included in cash payment to pre-IPO stockholders pursuant to tax receivable agreement		300,000
Estimated remaining cash payment to pre-IPO stockholders			9,484,000	27,399,000
Initial Public Offering [Line Items]
Shares issued in initial public offering (in shares)						15,600,000
Incurred costs							$ 2,250,000	$ 500,000
Conversion ratio for class B common stock to common stock (in shares)					1