Postretirement Benefits (Details 10) (Employee pension plan, USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair value measurements of pension plan assets:
Total	$ 548	$ 462	$ 411
Level 1
Fair value measurements of pension plan assets:
Total	3	4
Level 2
Fair value measurements of pension plan assets:
Total	545	458
Level 3
Fair value measurements of pension plan assets:
Total	0	0
Total equity securities
Fair value measurements of pension plan assets:
Total	308	259
Total equity securities | Level 1
Fair value measurements of pension plan assets:
Total	0	0
Total equity securities | Level 2
Fair value measurements of pension plan assets:
Total	308	259
Total equity securities | Level 3
Fair value measurements of pension plan assets:
Total	0	0
U.S. equity securities
Fair value measurements of pension plan assets:
Total	202	165
U.S. equity securities | Level 1
Fair value measurements of pension plan assets:
Total	0	0
U.S. equity securities | Level 2
Fair value measurements of pension plan assets:
Total	202	165
U.S. equity securities | Level 3
Fair value measurements of pension plan assets:
Total	0	0
Non-U.S. equity securities
Fair value measurements of pension plan assets:
Total	106	94
Non-U.S. equity securities | Level 1
Fair value measurements of pension plan assets:
Total	0	0
Non-U.S. equity securities | Level 2
Fair value measurements of pension plan assets:
Total	106	94
Non-U.S. equity securities | Level 3
Fair value measurements of pension plan assets:
Total	0	0
Debt securities
Fair value measurements of pension plan assets:
Total	237	199
Debt securities | Level 1
Fair value measurements of pension plan assets:
Total	0	0
Debt securities | Level 2
Fair value measurements of pension plan assets:
Total	237	199
Debt securities | Level 3
Fair value measurements of pension plan assets:
Total	0	0
Other
Fair value measurements of pension plan assets:
Total	3	4
Other | Level 1
Fair value measurements of pension plan assets:
Total	3	4
Other | Level 2
Fair value measurements of pension plan assets:
Total	0	0
Other | Level 3
Fair value measurements of pension plan assets:
Total	$ 0	$ 0