Shareholders' Equity (Details)	1 Months Ended					12 Months Ended					12 Months Ended	1 Months Ended	12 Months Ended
	Mar. 31, 2014 USD ($)	Sep. 30, 2013 USD ($)	Sep. 30, 2013 CHF	Sep. 30, 2012 USD ($)	Sep. 30, 2012 CHF	Mar. 31, 2014 USD ($)	Mar. 31, 2013 USD ($)	Mar. 31, 2014 CHF	Mar. 31, 2013 CHF	Sep. 30, 2008	Mar. 31, 2014 March 2014 USD ($)	Sep. 30, 2012 September 2008 - amended	Mar. 31, 2014 September 2008 - amended USD ($)	Mar. 31, 2013 September 2008 - amended USD ($)	Mar. 31, 2014 September 2008 USD ($)	Mar. 31, 2012 September 2008 USD ($)
Shareholders' Equity
Nominal share capital issued	$ 30,148,000					$ 30,148,000	$ 30,148,000	43,276,655
Shares, issued	173,106,000			191,600,000	191,600,000	173,106,000	173,106,000
Shares, par value (in CHF per share)								0.25	0.25
Treasury, at cost, shares	10,206,000					10,206,000	13,855,000
Conditional capital reserved for potential issuance on exercise of rights under employee equity incentive plans (in shares)										25,000,000
Conditional capital reserved for potential issuance to cover conversion rights under future convertible bond issuance (in shares)										25,000,000
Share Repurchases
Shares repurchased subject to cancellation												18,500,000
Shares, issued	173,106,000			191,600,000	191,600,000	173,106,000	173,106,000
Shares outstanding	173,106,000			191,600,000	191,600,000	173,106,000	173,106,000
Shares Approved, Shares	54,120,000					54,120,000				250,000,000	17,311,000		28,465,000		8,344,000
Shares Approved, Amount	250,000,000					677,030,000					250,000,000		177,030,000		250,000,000
Share Repurchases, Shares						26,109,000							18,500,000	8,600,000	7,609,000	17,500,000
Share Repurchases, Amount						243,848,000							170,714,000	87,800,000	73,134,000	156,000,000
Period for which repurchase program will remain in effect						3 years
Shares cancelled							18,500,000
Dividends
Unappropriated retained earnings	518,100,000					518,100,000		458,500,000
Approved dividend out of retained earnings			33,700,000		125,700,000
Cash dividends per share (units per share)		$ 0.22	0.21	$ 0.85	0.79	$ 0.22	$ 0.85
Dividends paid		36,100,000	33,700,000	133,500,000	125,700,000	36,123,000	133,462,000
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%
Portion of appropriated retained earnings representing legal reserves	10,800,000					10,800,000
Portion of appropriated retained earnings representing reserves for treasury shares	$ 118,400,000					$ 118,400,000