Pension and Postretirement Benefits (Plan Assets by Percentage Allocation) (Details)	Dec. 31, 2017	Dec. 31, 2016
Domestic Plan | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	0.00%	0.00%
Plan assets, actual allocation (as a percent)	1.00%	0.00%
Domestic Plan | U.S. Large Cap
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	0.00%	19.00%
Plan assets, actual allocation (as a percent)	0.00%	20.00%
Domestic Plan | U.S. Small Cap
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	0.00%	4.00%
Plan assets, actual allocation (as a percent)	0.00%	4.00%
Domestic Plan | International Large Cap
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	0.00%	14.00%
Plan assets, actual allocation (as a percent)	0.00%	14.00%
Domestic Plan | Emerging Markets
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	0.00%	5.00%
Plan assets, actual allocation (as a percent)	0.00%	5.00%
Domestic Plan | World Equity
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	0.00%	8.00%
Plan assets, actual allocation (as a percent)	0.00%	8.00%
Domestic Plan | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	48.00%	50.00%
Plan assets, actual allocation (as a percent)	48.00%	51.00%
Domestic Plan | Diversified Credit
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	12.00%	0.00%
Plan assets, actual allocation (as a percent)	12.00%	0.00%
Domestic Plan | Liability Driven Investment
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	40.00%	40.00%
Plan assets, actual allocation (as a percent)	39.00%	39.00%
Domestic Plan | Long-Term Government/Credit
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	0.00%	10.00%
Plan assets, actual allocation (as a percent)	0.00%	10.00%
Domestic Plan | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	52.00%	50.00%
Plan assets, actual allocation (as a percent)	51.00%	49.00%
Domestic Plan | Global Equity
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	36.00%	0.00%
Plan assets, actual allocation (as a percent)	36.00%	0.00%
Domestic Plan | Global Real Assets
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	12.00%	0.00%
Plan assets, actual allocation (as a percent)	12.00%	0.00%
Foreign Plan | Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	3.00%	4.00%
Plan assets, actual allocation (as a percent)	3.00%	4.00%
Foreign Plan | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	6.00%	11.00%
Plan assets, actual allocation (as a percent)	6.00%	11.00%
Foreign Plan | Liability Driven Investment
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	9.00%	11.00%
Plan assets, actual allocation (as a percent)	9.00%	11.00%
Foreign Plan | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	53.00%	45.00%
Plan assets, actual allocation (as a percent)	53.00%	45.00%
Foreign Plan | North American Companies
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	3.00%	3.00%
Plan assets, actual allocation (as a percent)	3.00%	3.00%
Foreign Plan | Global Equity
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	3.00%	8.00%
Plan assets, actual allocation (as a percent)	3.00%	8.00%
Foreign Plan | U.K. Government Gilt Index
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	41.00%	31.00%
Plan assets, actual allocation (as a percent)	41.00%	31.00%
Foreign Plan | U.K. Corporate Bond Index
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	1.00%	1.00%
Plan assets, actual allocation (as a percent)	1.00%	1.00%
Foreign Plan | Global Index Income Bond
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	2.00%	2.00%
Plan assets, actual allocation (as a percent)	2.00%	2.00%
Foreign Plan | Multi-Asset Category
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	22.00%	25.00%
Plan assets, actual allocation (as a percent)	22.00%	25.00%
Foreign Plan | Buy-in Contract
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	10.00%	9.00%
Plan assets, actual allocation (as a percent)	10.00%	9.00%
Foreign Plan | Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	6.00%	6.00%
Plan assets, actual allocation (as a percent)	6.00%	6.00%
Foreign Plan | Other Types
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation (as a percent)	38.00%	40.00%
Plan assets, actual allocation (as a percent)	38.00%	40.00%