Subsequent events (Details) (Subsequent events) In Millions, except Per Share data, unless otherwise specified		12 Months Ended
Nov. 12, 2014 CHF	Mar. 31, 2014 ESPP USD ($)
Subsequent events
Amount of one-time payment to each participant of the offering expressed as percentage of amount of shares that would have been purchased pursuant to the ESPP		15.00%
Additional compensation cost		$ 0
Dividend declared (in CHF per share)	0.2625

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

Name:	us-gaap_DividendsPayableAmountPerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant