Shareholders' Equity - Narrative (Details) SFr / shares in Units, $ / shares in Units, $ in Thousands, SFr in Millions |
1 Months Ended | 3 Months Ended | 6 Months Ended | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Sep. 30, 2025
USD ($)
shares
|
Sep. 30, 2023
shares
|
Jun. 30, 2025
USD ($)
shares
|
Mar. 31, 2025
USD ($)
|
Jun. 30, 2023
USD ($)
|
Sep. 30, 2025
USD ($)
SFr / shares
shares
|
Sep. 30, 2025
USD ($)
$ / shares
shares
|
Sep. 30, 2024
SFr / shares
|
Sep. 30, 2024
USD ($)
$ / shares
|
Sep. 30, 2025
USD ($)
SFr / shares
shares
|
Sep. 30, 2025
USD ($)
$ / shares
shares
|
Sep. 30, 2024
SFr / shares
|
Sep. 30, 2024
USD ($)
$ / shares
|
Sep. 30, 2025
CHF (SFr)
SFr / shares
shares
|
Mar. 31, 2025
SFr / shares
|
Mar. 31, 2025
USD ($)
shares
|
|
| Class of Stock [Line Items] | ||||||||||||||||
| Nominal share capital issued (CHF) | SFr | SFr 40.2 | |||||||||||||||
| Shares issued (in shares) | 160,784,460 | 160,784,460 | 160,784,460 | 160,784,460 | 160,784,460 | 160,784,460 | 168,994,000 | |||||||||
| Shares, par value (in CHF per share) | SFr / shares | SFr 0.25 | SFr 0.25 | ||||||||||||||
| Treasury, at cost, shares (in shares) | 13,889,105 | 13,889,105 | 13,889,105 | 13,889,105 | 13,889,105 | 13,889,105 | 20,485,000 | |||||||||
| Adjusted share capital period (in years) | 5 years | 5 years | ||||||||||||||
| Maximum percentage of shares held by the company and its subsidiaries | 10.00% | 10.00% | 10.00% | 10.00% | 10.00% | 10.00% | ||||||||||
| Maximum shares available for purchase (in shares) | 16,100,000 | 16,100,000 | 16,100,000 | 16,100,000 | 16,100,000 | 16,100,000 | ||||||||||
| Shares acquired for cancellation (in shares) | 900,000 | |||||||||||||||
| Shares acquired for equity incentive plans or potential acquisitions (in shares) | 13,000,000 | |||||||||||||||
| Cash dividends per share declared (in dollars per share) | (per share) | SFr 1.26 | $ 1.58 | SFr 1.16 | $ 1.37 | SFr 1.26 | $ 1.58 | SFr 1.16 | $ 1.37 | ||||||||
| Payment of cash dividends | $ | $ 233,100 | $ 207,900 | $ 233,059 | $ 207,853 | ||||||||||||
| Common Stock Capital Shares Reserved For Future Issuance Employee Equity Incentive Plans | ||||||||||||||||
| Class of Stock [Line Items] | ||||||||||||||||
| Shares that may be issued out of conditional capital (in shares) | 25,000,000 | 25,000,000 | 25,000,000 | 25,000,000 | 25,000,000 | 25,000,000 | ||||||||||
| Common Stock Capital Shares Reserved For Future Issuance Conversion Rights Under Future Convertible Bond Issuance | ||||||||||||||||
| Class of Stock [Line Items] | ||||||||||||||||
| Shares that may be issued out of conditional capital (in shares) | 25,000,000 | 25,000,000 | 25,000,000 | 25,000,000 | 25,000,000 | 25,000,000 | ||||||||||
| Minimum | ||||||||||||||||
| Class of Stock [Line Items] | ||||||||||||||||
| Number of adjusted share capital (in shares) | 144,706,014 | 155,795,958 | 144,706,014 | 144,706,014 | 144,706,014 | 144,706,014 | 144,706,014 | |||||||||
| Maximum | ||||||||||||||||
| Class of Stock [Line Items] | ||||||||||||||||
| Number of adjusted share capital (in shares) | 176,862,906 | 190,417,282 | 176,862,906 | 176,862,906 | 176,862,906 | 176,862,906 | 176,862,906 | |||||||||
| 2023 Share Repurchase Program | ||||||||||||||||
| Class of Stock [Line Items] | ||||||||||||||||
| Period for which repurchase program will remain in effect (in years) | 3 years | |||||||||||||||
| Share repurchase, authorized amount (up to) | $ | $ 1,000,000 | $ 1,600,000 | ||||||||||||||
| Increase in authorized amount under share repurchase program | $ | $ 600,000 | |||||||||||||||
| Amount available for repurchase | $ | $ 432,700 | SFr 432,700 | $ 432,700 | SFr 432,700 | $ 432,700 | |||||||||||
| Cancellation of treasury shares (in shares) | 8,200,000 | |||||||||||||||
| Treasury shares repurchased | $ | $ 712,200 | |||||||||||||||