Shareholders' Equity (Details) $ / shares in Units, shares in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
|
Mar. 31, 2024
USD ($)
$ / shares
shares
|
Mar. 31, 2023
USD ($)
$ / shares
shares
|
Mar. 31, 2024
USD ($)
$ / shares
shares
|
Mar. 31, 2023
USD ($)
$ / shares
shares
|
|
| Equity, Class of Treasury Stock [Line Items] | ||||
| Purchased call option strike price for share repurchase contracts | 0 | 0 | ||
| Written Call Option Strike Price for share repurchase contracts | 99.45 | 99.45 | ||
| Payment for share repurchase contracts | $ (50,000,000.0) | $ 0 | ||
| Share repurchase contracts - number of shares received | shares | 0.5 | 0.5 | ||
| Common Stock | ||||
| Equity, Class of Treasury Stock [Line Items] | ||||
| Shares repurchased | shares | 0.1 | 0.7 | 0.5 | 1.0 |
| Average price per share (a) | $ / shares | $ 103.88 | $ 88.59 | $ 87.23 | $ 87.47 |
| Total Share Repurchase Cost | $ 8,100,000 | $ 59,700,000 | $ 44,800,000 | $ 83,700,000 |