Shareholders' Equity (Details) SFr / shares in Units, $ / shares in Units, $ in Millions, SFr in Billions				1 Months Ended				7 Months Ended	9 Months Ended	12 Months Ended
	Dec. 09, 2016 shares	Mar. 18, 2015 USD ($)	Mar. 19, 2014 USD ($)	May 31, 2015 USD ($) installment $ / shares	May 31, 2014 USD ($) installment $ / shares	May 31, 2009 CHF (SFr)	May 31, 2009 USD ($)	Dec. 31, 2014 USD ($) item	Sep. 30, 2015 USD ($) item	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) item	Dec. 31, 2016 subsidiary SFr / shares shares	Dec. 31, 2015 SFr / shares shares	Oct. 29, 2015 SFr / shares	Oct. 29, 2015 USD ($)	May 31, 2013 item $ / shares
Par value reduction
Approved par value of common stock (in Swiss francs per share) | SFr / shares														SFr 0.10
Par value of common stock (in Swiss francs per share) | SFr / shares												SFr 0.10	SFr 15.00	SFr 15.00
Distribution of qualifying additional paid-in capital
Cash distribution approved in the form of additional paid-in capital (in dollars per share) | $ / shares				$ 0.60	$ 3.00											$ 2.24
Number of quarterly installments (in installments)				4	4											4
Amount of installment (in dollars per share) | $ / shares				$ 0.15	$ 0.75											$ 0.56
Liability for distribution payable | $				$ 218	$ 1,100
Number of installments paid (in installments) | item								3	2		3
Installment of dividend paid | $		$ 272	$ 202					$ 816	$ 109	$ 381	$ 1,018
Cancellation of previously declared dividend | $															$ 109
Total number of securities issued in merger	23,800,000
Total number of securities issued in merger	1.20
Shares held in treasury
Authorized amount for repurchase of shares						SFr 3.5	$ 3,400
Treasury shares													2,863,267
Shares held by subsidiary
Number of subsidiaries to whom shares were issued | subsidiary												2
Number of shares held by subsidiary												5,400,000	6,900,000