Stock-Based Compensation	12 Months Ended
Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	11. STOCK-BASED COMPENSATION: We account for our stock-based compensation plans following the provisions of FASB Accounting Standards Codification 718, “Compensation — Stock Compensation” (“ASC 718”). In accordance with ASC 718, we use the Black-Scholes valuation model for valuing all stock-based compensation and shares purchased under our Employee Stock Purchase Plan. We measure compensation for restricted stock awards and restricted stock units at fair value on the grant date based on the number of shares expected to vest and the quoted market price of our common stock. We recognize compensation cost for all awards in operations, net of estimated forfeitures, on a straight-line basis over the requisite service period for each separately vesting portion of the award. Cash received from option exercises under all share-based compensation arrangements for the fiscal years ended September 30, 2016, 2017, and 2018 was approximately $2.7 million, $3.2 million, and $7.7 million, respectively. We currently expect to satisfy share-based awards with registered shares available to be issued.

Stock-Based Compensation

12 Months Ended

Sep. 30, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

11. STOCK-BASED COMPENSATION:

We account for our stock-based compensation plans following the provisions of FASB Accounting Standards Codification 718, “Compensation — Stock Compensation” (“ASC 718”). In accordance with ASC 718, we use the Black-Scholes valuation model for valuing all stock-based compensation and shares purchased under our Employee Stock Purchase Plan. We measure compensation for restricted stock awards and restricted stock units at fair value on the grant date based on the number of shares expected to vest and the quoted market price of our common stock. We recognize compensation cost for all awards in operations, net of estimated forfeitures, on a straight-line basis over the requisite service period for each separately vesting portion of the award.

Cash received from option exercises under all share-based compensation arrangements for the fiscal years ended September 30, 2016, 2017, and 2018 was approximately $2.7 million, $3.2 million, and $7.7 million, respectively. We currently expect to satisfy share-based awards with registered shares available to be issued.