Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2013	Sep. 30, 2012
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 4,088	$ 4,067
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Treasury stock, shares	626,225
Class A Common Stock
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	950,000,000	950,000,000
Common stock, shares issued	93,912,729	93,087,049
Common stock, shares outstanding	93,912,729	93,087,049
Class B Convertible Redeemable Common Stock
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	2,000,000	2,000,000
Common stock, shares issued	0	0
Common stock, shares outstanding	0	0