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
shares
|
Sep. 30, 2023
shares
|
Sep. 30, 2026
USD ($)
shares
|
Mar. 31, 2026
SFr / shares
|
Jun. 30, 2025
USD ($)
shares
|
Mar. 31, 2025
USD ($)
|
Jun. 30, 2023
USD ($)
|
Sep. 30, 2026
USD ($)
SFr / shares
shares
|
Sep. 30, 2026
USD ($)
$ / shares
shares
|
Sep. 30, 2025
SFr / shares
shares
|
Sep. 30, 2025
USD ($)
$ / shares
shares
|
Sep. 30, 2026
USD ($)
SFr / shares
shares
|
Sep. 30, 2026
USD ($)
$ / shares
shares
|
Sep. 30, 2025
SFr / shares
shares
|
Sep. 30, 2025
USD ($)
$ / shares
shares
|
Sep. 30, 2026
CHF (SFr)
SFr / shares
shares
|
Mar. 31, 2026
USD ($)
shares
|
|
| Class of Stock [Line Items] | |||||||||||||||||
| Common stock outstanding | $ 28,001 | $ 28,001 | $ 28,001 | $ 28,001 | $ 28,001 | SFr 40.2 | $ 28,001 | ||||||||||
| Shares issued (in shares) | 160,784,460 | 160,784,460 | 160,784,460 | 160,784,460 | 160,784,460 | 160,784,460 | 160,784,000 | ||||||||||
| Shares, par value (in CHF per share) | SFr / shares | SFr 0.25 | SFr 0.25 | |||||||||||||||
| Treasury, at cost, shares (in shares) | 18,583,859 | 18,583,859 | 18,583,859 | 18,583,859 | 18,583,859 | 18,583,859 | 17,282,000 | ||||||||||
| 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) | 7,300,000 | ||||||||||||||||
| Shares acquired for equity incentive plans or potential acquisitions (in shares) | 11,300,000 | ||||||||||||||||
| Cash dividends per share (in dollars per share) | (per share) | $ 1.36 | $ 1.68 | SFr 1.26 | $ 1.58 | $ 1.36 | $ 1.68 | SFr 1.26 | $ 1.58 | |||||||||
| Payment of cash dividends | $ | $ 235,300 | $ 233,100 | $ 235,343 | $ 233,059 | |||||||||||||
| 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) | $ | $ 1,600,000 | $ 1,000,000 | |||||||||||||||
| Increase in authorized amount under share repurchase program | $ | $ 600,000 | ||||||||||||||||
| Cancellation of treasury shares (in shares) | 4,600,000 | 8,200,000 | |||||||||||||||
| Treasury shares repurchased | $ | $ 432,100 | $ 712,200 | |||||||||||||||
| 2026 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) | $ | $ 1,400,000 | ||||||||||||||||
| Share repurchase program, authorized (in shares) | 16,078,446 | ||||||||||||||||
| Amount available for repurchase | $ | $ 1,100,000 | $ 1,100,000 | $ 1,100,000 | $ 1,100,000 | $ 1,100,000 | ||||||||||||
| Capital shares reserved for future 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 | |||||||||||
| Capital shares reserved for future issuance under 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 | |||||||||||
| 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 | |||||||||||