Summary of Significant Accounting Policies - Shares Used in Computing Basic and Diluted Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Denominator (thousands of shares):
Weighted-average common shares outstanding - basic (in shares)	173,742	173,395	173,625	172,954
Incremental shares issuable for stock options and awards (in shares)	0	2,579	3,500	2,306
Weighted-average common shares outstanding - diluted (in shares)	173,742	175,974	177,125	175,260
Antidilutive shares excluded from calculation of earnings per share	3,556