Stock-Based Compensation and Employee Benefit Plans (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended				1 Months Ended	12 Months Ended								12 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2010 Predecessor	Sep. 30, 2012 Senior management	Sep. 30, 2012 Other management	Oct. 31, 2012 Stock option	Sep. 30, 2012 Stock option	Sep. 30, 2011 Stock option	Sep. 30, 2010 Stock option Predecessor	Sep. 30, 2012 Time-based stock option awards	Sep. 30, 2011 Time-based stock option awards	Sep. 30, 2012 Performance based awards	Sep. 30, 2011 Performance based awards	Nov. 30, 2010 Class A common stock	Sep. 30, 2011 Class A common stock Stock option	Nov. 30, 2010 Class B common stock	Sep. 30, 2012 Class B common stock Stock option	Sep. 30, 2011 Class B common stock Stock option
Stock-Based Compensation and Employee Benefit Plans
Aggregate number of shares which may be issued													50,268		148,404
Expiration period	10 years							10 years
Vesting period						5 years			5 years
Amount that the holder is entitled to receive in excess of the per-share exercise price upon cancellation of options (in dollars per share)								$ 55.00
Weighted-average grant date fair value (in dollars per share)								$ 22.13	$ 239.00	$ 180.00	$ 108.00	$ 56
Dividend paid					$ 722,000
Weighted-average assumptions used for the options granted
Risk-free rate, minimum (as a percent)									0.10%	0.12%	0.10%	0.12%
Risk-free rate, maximum (as a percent)									3.12%	4.50%	3.12%	4.50%
Risk-free rate (as a percent)								2.90%
Expected term								6 years 4 months 24 days	6 years 6 months	6 years 6 months	5 years 7 months 6 days	6 years 7 months 6 days
Expected volatility (as a percent)								48.00%	37.00%	33.00%	38.00%	34.00%
Expected dividends (as a percent)								0.00%	0.00%	0.00%	0.00%	0.00%
Number of shares
Outstanding at beginning of period (in shares)					162,951	152,678		3,765
Granted (in shares)						24,850	153,178	287						49,468		24,850	103,710
Exercised (in shares)						(450)		(1,570)
Forfeited (in shares)						(14,127)	(500)	(28)
Outstanding at end of period (in shares)						162,951	152,678	2,454
Exercisable at end of period (in shares)						14,357		838
Number of shares available for future grant (in shares)						34,782
Weighted average exercise price
Outstanding at beginning of period (in dollars per share)					$ 527.00	$ 500.00		$ 14.38
Granted (in dollars per share)						$ 675.00	$ 500.00	$ 43.88
Exercised (in dollars per share)						$ 500.00		$ 6.76
Forfeited (in dollars per share)						$ 500.00	$ 500.00	$ 26.10
Outstanding at end of period (in dollars per share)						$ 527.00	$ 500.00	$ 22.57
Exercisable at end of period (in dollars per share)						$ 500.00		$ 12.08
Additional disclosures
Reduction in percentage of share-based compensation expense for estimated forfeitures			0.00%	5.00%
Stock option exercise and related activity
Stock options exercised (in shares)						450		1,570
Aggregate proceeds		10,621						10,613
Compensation deduction for tax purposes								6,940
Tax benefit credited to capital in excess of par		6,646						6,646
Intrinsic value of options exercised								$ 55,383