Legal Reserves [Abstract]

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- Definition

Legal Reserves Threshold At Which Annual Net Income Not Required To Be Retained

+ References

No definition available.

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- Definition

Represents the minimum percentage of annual net income to be retained in legal reserves.

+ References

No definition available.

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- Definition

A segregation of the portion of retained earnings which is unavailable for dividend distribution representing legal reserves.

+ References

No definition available.

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- Definition

Share Repurchases [Abstract]

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No definition available.

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- Definition

Shares authorized by shareholders for future issuance on conversion or exercise of derivative securities.

+ References

No definition available.

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- Definition

Aggregate dividends paid during the period for each share of common stock outstanding.

+ References

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- Definition

Face amount or stated value per share of common stock.

+ References

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- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

+ References

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- Definition

Aggregate par or stated value of issued nonredeemable common stock (or common stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable common shares, par value and other disclosure concepts are in another section within stockholders' equity.

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- References

No definition available.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Cash outflow in the form of ordinary dividends to common shareholders, preferred shareholders and noncontrolling interests, generally out of earnings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

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- Definition

A segregation of retained earnings which is available for dividend distribution. Earnings not paid out as dividends but instead reinvested in the core business or used to pay off debt. Unappropriated profit is part of shareholder equity. Also called cumulative distributions or earned surplus or accumulated earnings or unappropriated profit.

+ References

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- Definition

Amount of stock repurchase plan authorized.

+ References

No definition available.

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- Definition

Period which shares may be purchased under a stock repurchase plan authorized by an entity's Board of Directors, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB
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- Definition

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB
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-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

+ References

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Shareholders' Equity (Narrative) (Details) SFr / shares in Units, $ / shares in Units, SFr in Millions	1 Months Ended								11 Months Ended	12 Months Ended			38 Months Ended
	May 31, 2018 USD ($)	May 31, 2018 CHF (SFr)	Sep. 30, 2017 SFr / shares	Sep. 30, 2017 USD ($) $ / shares	Sep. 30, 2016 SFr / shares	Sep. 30, 2016 USD ($) $ / shares	Sep. 30, 2015 SFr / shares	Sep. 30, 2015 USD ($) $ / shares	Mar. 31, 2018 USD ($) shares	Mar. 31, 2018 USD ($) $ / shares shares	Mar. 31, 2017 USD ($) $ / shares	Mar. 31, 2016 USD ($) $ / shares	Apr. 30, 2017 USD ($) shares	Mar. 31, 2018 CHF (SFr) SFr / shares shares	Mar. 31, 2017 SFr / shares	Mar. 31, 2017 USD ($) shares	Mar. 31, 2014 USD ($)
Shareholder's equity
Nominal share capital issued (CHF) \| SFr														SFr 43.3
Shares, issued (in shares) \| shares									173,106,620	173,106,620				173,106,620		173,106,620
Shares, par value (in CHF per share) \| SFr / shares														SFr 0.25	SFr 0.25
Treasury shares (in shares) \| shares									8,526,642	8,526,642				8,526,642		10,727,000
Conditionally authorized shares (in shares) \| shares									50,000,000	50,000,000				50,000,000		50,000,000
Dividends
Unappropriated retained earnings									$ 818,000,000	$ 818,000,000				SFr 782.3
Payment of cash dividends \| $				$ 104,200,000		$ 93,100,000		$ 85,900,000		$ 104,248,000	$ 93,093,000	$ 85,915,000
Cash dividends per share (in dollars/CHF per share) \| (per share)			SFr 0.61	$ 0.63	SFr 0.56	$ 0.57	SFr 0.51	$ 0.53		$ 0.63	$ 0.57	$ 0.53
Legal Reserves
Minimum percentage of annual net income to be retained in legal reserves										5.00%
Threshold of legal reserves as a percentage of issued and outstanding aggregate par value per share capital at which a minimum percentage of annual net income is no longer required to be retained									20.00%	20.00%				20.00%
Portion of appropriated retained earnings representing legal reserves \| $									$ 10,000,000	$ 10,000,000
Share Repurchases
Share repurchase, amount \| $										$ 30,722,000	$ 83,786,000	$ 70,358,000
Common Stock Capital Shares Reserved For Future Issuance Employee Equity Incentive Plans
Shareholder's equity
Conditionally authorized shares (in shares) \| shares									25,000,000	25,000,000				25,000,000
Common Stock Capital Shares Reserved For Future Issuance Conversion Rights Under Future Convertible Bond Issuance
Shareholder's equity
Conditionally authorized shares (in shares) \| shares									25,000,000	25,000,000				25,000,000
March 2014 program
Share Repurchases
Share repurchase, authorized amount \| $									$ 250,000,000	$ 250,000,000							$ 250,000,000.0
Purchases of registered shares (in shares) \| shares													9,113,000
Share repurchase, amount \| $													$ 155,983,000
March 2017 program
Share Repurchases
Share repurchase, authorized amount \| $									$ 250,000,000	$ 250,000,000						$ 250,000,000.0
Period for which repurchase program will remain in effect											3 years
Purchases of registered shares (in shares) \| shares									843,000
Share repurchase, amount \| $									$ 30,107,000
Scenario, Forecast \| Subsequent Event
Dividends
Payment of cash dividends	$ 115,700,000	SFr 110.7