Long-Term Employee Benefits (Contributions) (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2012	Dec. 31, 2013
Principal U.S. Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		$ 0	$ 500
Expected 2015 contributions to principal U.S. pension plan	50
Pension Plan Other Than Principal Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		190		197
Employer Contributions in 2015	about the same
Remaining pension plans with no plan assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		121		116
Employer Contributions in 2015	about the same
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		$ 233		$ 207
Employer Contributions in 2015	about the same