Pension and Other Retiree Benefits (Weighted Average Asset Allocation) (Details) - Pension		Dec. 31, 2017	Dec. 31, 2016
U.S.
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations		100.00%	100.00%
U.S. | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations		57.00%	68.00%
U.S. | Fixed income
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations		30.00%	25.00%
U.S. | Real estate
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations		6.00%	0.00%
U.S. | Other
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations	[1]	7.00%	7.00%
International
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations		100.00%	100.00%
International | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations		26.00%	33.00%
International | Fixed income
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations		29.00%	51.00%
International | Real estate
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations		5.00%	3.00%
International | Other
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocations	[1]	40.00%	13.00%

[1] Multi-strategy hedge funds, insurance contracts and cash and cash equivalents for certain of our plans.