Shareholders' equity (Detail)	2 Months Ended	12 Months Ended									0 Months Ended	2 Months Ended	12 Months Ended
	Feb. 27, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2013 CHF	Dec. 31, 2012 USD ($)	Dec. 31, 2012 CHF	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CHF	Dec. 31, 2013 General Purpose	Dec. 31, 2013 Issuance of Debt	Dec. 31, 2013 Employee Benefit Plans	Nov. 21, 2013 November 2013 Stock Repurchase Plan [Member] USD ($)	Feb. 27, 2014 November 2013 Stock Repurchase Plan [Member] USD ($)	Dec. 31, 2013 November 2013 Stock Repurchase Plan [Member] USD ($)
Stockholders' Equity Note [Abstract]
Dividend installments		$ 0.51
Common shares in treasury, shares		3,038,477	3,038,477	2,510,878	2,510,878	5,905,136	5,905,136
Conditional Share Issuance, by Scenario [Line Items]
Repurchase of outstanding common shares, shares	3,437,082	3,266,531	3,266,531	100,000	100,000	2,058,860	2,058,860
Cost of shares acquired	$ 326,000,000	$ 290,000,000		$ 7,000,000		$ 132,000,000
Authorized share capital for general purposes								140,000,000	33,000,000	25,410,929
Stock repurchase program authorized amount											2,000,000,000
Share repurchase authorization remaining												$ 1,620,000,000	$ 1,940,000,000
The number of votes associated with one Common Share		1	1
The maximum ownership percentage for voting allowed for any one shareholder		10.00%	10.00%
Par value reduction per common share					1.38
Dividends declared per common share		$ 2.02	1.85	$ 2.06	1.91	$ 1.38	1.22