Stockholders' Equity	12 Months Ended
Stockholders' Equity	Sep. 30, 2019
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders' Equity Share Repurchases On April 29, 2013, our Board of Directors approved a share repurchase program for up to $500.0 million, which was increased by $500.0 million on April 29, 2015. On August 1, 2018, our Board of Directors approved an additional $500.0 million under our share repurchase program. Under the terms of the share repurchase program, we have the ability to repurchase shares from time to time through a variety of methods, which may include open market purchases, privately negotiated transactions, block trades, accelerated share repurchase transactions, or any combination of such methods. The share repurchase program does not require us to acquire any specific number of shares and may be modified, suspended, extended or terminated by us at any time without prior notice. The timing and the amount of any purchases will be determined by management based on an evaluation of market conditions, capital allocation alternatives, and other factors. We repurchased 8.2 million shares, 9.7 million shares and 5.8 million shares for $126.9 million, $136.1 million and $99.1 million during the fiscal years ended September 30, 2019, 2018 and 2017, respectively, under the program. The amount paid in excess of par value is recognized in additional paid in capital and these shares were retired upon repurchase. Since the commencement of the program, we have repurchased 64.3 million shares for $1,070.0 million. The amount paid in excess of par value is recognized in additional paid in capital. Shares were retired upon repurchase. As of September 30, 2019, approximately $430.4 million remained available for share repurchases as of September 30, 2019 pursuant to our share repurchase program. Stock Issuances During the year ended September 30, 2017, we issued 844,108 shares of our common stock valued at $13.4 million in connection with a business acquisition and 175,000 shares of our common stock valued at $2.9 million associated with charitable contributions. There were no share issuances in connection with acquisitions in fiscal years 2018 and 2019. Preferred Stock We are authorized to issue up to 40,000,000 shares of preferred stock, par value $0.001 per share. The undesignated shares of preferred stock will have rights, preferences, privileges and restrictions, including voting rights, dividend rights, conversion rights, redemption privileges and liquidation preferences, as shall be determined by the Board of Directors upon issuance of the preferred stock. There were no outstanding shares of preferred stock as of September 30, 2019 or September 30, 2018. Series A Preferred Stock We have designated 1,000,000 shares as Series A Preferred Stock, par value $0.001 per share. The Series A Preferred Stock is entitled to receive dividends equal to the greater of $1.00 and 1,000 times the aggregate per share amount of all dividends declared on our Common Stock. Holders of each share of the Series A Preferred Stock are entitled to 1,000 votes on all matters submitted to a vote of the stockholders of the Company, and shall vote as one class. The Series A Preferred Stock is not redeemable, and has the right to certain liquidation preferences over our Common Stock. The Series A Preferred Stock ranks junior to all other series of the Preferred Stock as to the payment of dividends and the distribution of assets. There were no outstanding shares of preferred stock as of September 30, 2019 or September 30, 2018. Series B Preferred Stock We have designated 15,000,000 shares as Series B Preferred Stock, par value $0.001 per share. The Series B Preferred Stock is convertible into shares of common stock on a one-for-one basis and has a liquidation preference of $1.30 per share plus all declared but unpaid dividends. The holders of Series B Preferred Stock are entitled to non-cumulative dividends at the rate of $0.05 per annum per share, payable when, and if, declared by the Board of Directors. To date, no dividends have been declared by the Board of Directors. Holders of Series B Preferred Stock have no voting rights, except those rights provided under Delaware law. There were no outstanding shares of preferred stock as of September 30, 2019 or September 30, 2018.