Pension and Postretirement Expense Level 4 (Details) - U.S. Pension Plan Investments Measured at Fair Value - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
investment receivable	$ 0	$ 12
Pension Plan [Member] | UNITED STATES
Large Cap Equity Funds	38	35
Small mid Cap Equity Funds	6	6
Other International Equity	30	25
Debt Securities Fixed Income	116	110
Cash, Money Market and Other	6	4
Pension Benefits Fair Value of Plan Assets of Underfunded Plans	213	207
Fair value of plan assets at end of year subtotal	196	180
Other funds	17	15
Pension Plan [Member] | UNITED STATES | Fair Value, Inputs, Level 1 [Member]
Large Cap Equity Funds	0	0
Small mid Cap Equity Funds	0	0
Other International Equity	0	0
Debt Securities Fixed Income	0	0
Cash, Money Market and Other	0	0
Pension Benefits Fair Value of Plan Assets of Underfunded Plans	0	0
Pension Plan [Member] | UNITED STATES | Fair Value, Inputs, Level 2 [Member]
Large Cap Equity Funds	38	35
Small mid Cap Equity Funds	6	6
Other International Equity	30	25
Debt Securities Fixed Income	116	110
Cash, Money Market and Other	6	4
Pension Benefits Fair Value of Plan Assets of Underfunded Plans	196	180
Pension Plan [Member] | UNITED STATES | Fair Value, Inputs, Level 3 [Member]
Large Cap Equity Funds	0	0
Small mid Cap Equity Funds	0	0
Other International Equity	0	0
Debt Securities Fixed Income	0	0
Cash, Money Market and Other	0	0
Pension Benefits Fair Value of Plan Assets of Underfunded Plans	$ 0	$ 0