Shareholders' Equity (Detail) In Millions, except Share data, unless otherwise specified	1 Months Ended		3 Months Ended				6 Months Ended
	Aug. 31, 2011 USD ($)	Nov. 30, 2010 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2013 CHF	Jun. 30, 2012 USD ($)	Jun. 30, 2012 CHF	Jun. 30, 2013 USD ($)	Jun. 30, 2013 CHF	Jun. 30, 2012 USD ($)	Jun. 30, 2012 CHF	Dec. 31, 2012 CHF
Stockholders' Equity Note [Abstract]
Dividends declared per common share			$ 0.51	0.48	$ 0.49	0.48	$ 1.00	0.94	$ 1.08	1.01
Common Shares, par value				27.95				27.95			28.89
Common Shares in treasury, shares			2,746,143	2,746,143			2,746,143	2,746,143			2,510,878
Stock repurchase program, authorized amount	$ 303	$ 600
Share repurchase authorization remains	197						249
Repurchase of outstanding common shares, shares			654,776	654,776			2,463,076	2,463,076
Share repurchase amount			$ 58				$ 212
Increase to dividend approved by shareholders in January									$ 0.12