Income Taxes	9 Months Ended
Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Effective Tax Rate The effective income tax rate was 28.6% and 30.4% during the quarters ended June 30, 2017 and 2016, respectively and 9.2% and 27.2% during the nine months ended June 30, 2017 and 2016, respectively. The provision for income taxes during interim quarterly reporting periods is based on our estimates of the effective tax rates for the full fiscal year. The effective tax rate in any quarter can also be affected positively or negatively by adjustments that are required to be reported in the specific quarter of resolution. The effective tax rate for the nine months ended June 30, 2017 was significantly impacted by the recording of excess tax benefits relating to stock awards that vested in December 2016. As a result of the adoption of ASU 2016-09 on October 1, 2016, we no longer record excess tax benefits as an increase to additional paid-in capital, but record such excess tax benefits on a prospective basis as a reduction of income tax expense, which amounted to $23.5 million for the nine months ended June 30, 2017. We also anticipate the potential for increased periodic volatility in future effective tax rates as the impact of the continued application of ASU 2016-09 is dependent upon our future grants of stock-based compensation, our future stock price in relation to the fair value of awards on grant date and the exercise behavior of our stock option holders. The total unrecognized tax benefit for uncertain tax positions is estimated to be approximately $7.8 million and $6.8 million at June 30, 2017 and September 30, 2016, respectively. We recognize interest expense related to unrecognized tax benefits and penalties as part of the provision for income taxes in our condensed consolidated statements of income and comprehensive income. We have accrued interest of $0.5 million and $0.3 million related to unrecognized tax benefits as of June 30, 2017 and September 30, 2016, respectively.

Income Taxes

9 Months Ended

Jun. 30, 2017

Effective Tax Rate

The effective income tax rate was 28.6% and 30.4% during the quarters ended June 30, 2017 and 2016, respectively and 9.2% and 27.2% during the nine months ended June 30, 2017 and 2016, respectively. The provision for income taxes during interim quarterly reporting periods is based on our estimates of the effective tax rates for the full fiscal year. The effective tax rate in any quarter can also be affected positively or negatively by adjustments that are required to be reported in the specific quarter of resolution. The effective tax rate for the nine months ended June 30, 2017 was significantly impacted by the recording of excess tax benefits relating to stock awards that vested in December 2016. As a result of the adoption of ASU 2016-09 on October 1, 2016, we no longer record excess tax benefits as an increase to additional paid-in capital, but record such excess tax benefits on a prospective basis as a reduction of income tax expense, which amounted to $23.5 million for the nine months ended June 30, 2017. We also anticipate the potential for increased periodic volatility in future effective tax rates as the impact of the continued application of ASU 2016-09 is dependent upon our future grants of stock-based compensation, our future stock price in relation to the fair value of awards on grant date and the exercise behavior of our stock option holders.

The total unrecognized tax benefit for uncertain tax positions is estimated to be approximately $7.8 million and $6.8 million at June 30, 2017 and September 30, 2016, respectively. We recognize interest expense related to unrecognized tax benefits and penalties as part of the provision for income taxes in our condensed consolidated statements of income and comprehensive income. We have accrued interest of $0.5 million and $0.3 million related to unrecognized tax benefits as of June 30, 2017 and September 30, 2016, respectively.