Pension and Other Postretirement Benefits (Details 3) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
North America
Pension and Other Postretirement Benefits
Total assets		$ 636.0
Pension Plans | Pooled Equity Funds [Member]
Pension and Other Postretirement Benefits
Total assets		41.0
Pension Plans | Pooled mutual funds(5)
Pension and Other Postretirement Benefits
Total assets		86.0
Pension Plans | North America
Pension and Other Postretirement Benefits
Defined Benefit Plan, Plan with Benefit Obligation in Excess of Plan Assets, Benefit Obligation	$ 759.0	712.0
Total assets at fair value by fair value levels	737.0	637.0
Receivables—net	1.0	(1.0)
Total assets	738.0	636.0	$ 627.0
Pension Plans | North America | Cash and cash equivalents
Pension and Other Postretirement Benefits
Total assets	26.0	39.0
Pension Plans | North America | Equity mutual funds: Index equity
Pension and Other Postretirement Benefits
Total assets	136.0	112.0
Pension Plans | North America | Pooled Equity Funds [Member]
Pension and Other Postretirement Benefits
Total assets	42.0
Pension Plans | North America | Fixed income: U.S.Treasury bonds and notes
Pension and Other Postretirement Benefits
Total assets	15.0	14.0
Pension Plans | North America | Pooled mutual funds(5)
Pension and Other Postretirement Benefits
Total assets	106.0
Pension Plans | North America | Fixed income: Corporate bonds and notes
Pension and Other Postretirement Benefits
Total assets	400.0	329.0
Pension Plans | North America | Fixed income: Government and agency securities
Pension and Other Postretirement Benefits
Total assets	9.0	15.0
Pension Plans | North America | Fixed income: Other
Pension and Other Postretirement Benefits
Total assets	3.0	1.0
Pension Plans | North America | Equity pooled mutual funds
Pension and Other Postretirement Benefits
Total assets at fair value by fair value levels		0.0
Pension Plans | North America | Quoted Prices in Active Markets (Level 1)
Pension and Other Postretirement Benefits
Total assets at fair value by fair value levels	151.0	132.0
Pension Plans | North America | Quoted Prices in Active Markets (Level 1) | Cash and cash equivalents
Pension and Other Postretirement Benefits
Total assets	0.0	6.0
Pension Plans | North America | Quoted Prices in Active Markets (Level 1) | Equity mutual funds: Index equity
Pension and Other Postretirement Benefits
Total assets	136.0	112.0
Pension Plans | North America | Quoted Prices in Active Markets (Level 1) | Fixed income: U.S.Treasury bonds and notes
Pension and Other Postretirement Benefits
Total assets	15.0	14.0
Pension Plans | North America | Significant Other Observable Inputs (Level 2)
Pension and Other Postretirement Benefits
Total assets at fair value by fair value levels	586.0	505.0
Total assets		33.0
Pension Plans | North America | Significant Other Observable Inputs (Level 2) | Cash and cash equivalents
Pension and Other Postretirement Benefits
Total assets	26.0
Pension Plans | North America | Significant Other Observable Inputs (Level 2) | Pooled Equity Funds [Member]
Pension and Other Postretirement Benefits
Total assets	42.0	41.0
Pension Plans | North America | Significant Other Observable Inputs (Level 2) | Pooled mutual funds(5)
Pension and Other Postretirement Benefits
Total assets	106.0	86.0
Pension Plans | North America | Significant Other Observable Inputs (Level 2) | Fixed income: Corporate bonds and notes
Pension and Other Postretirement Benefits
Total assets	400.0	329.0
Pension Plans | North America | Significant Other Observable Inputs (Level 2) | Fixed income: Government and agency securities
Pension and Other Postretirement Benefits
Total assets	9.0	15.0
Pension Plans | North America | Significant Other Observable Inputs (Level 2) | Fixed income: Other
Pension and Other Postretirement Benefits
Total assets	3.0	1.0
Pension Plans | United Kingdom
Pension and Other Postretirement Benefits
Defined Benefit Plan, Plan with Benefit Obligation in Excess of Plan Assets, Benefit Obligation	590.0	559.0
Total assets at fair value by fair value levels	371.0	330.0
Total assets at fair value	414.0	366.0
Receivables—net	0.0	0.0
Total assets	414.0	366.0	$ 414.0
Pension Plans | United Kingdom | Cash and cash equivalents
Pension and Other Postretirement Benefits
Total assets	5.0	3.0
Pension Plans | United Kingdom | Pooled Target Return Funds
Pension and Other Postretirement Benefits
Total assets at fair value by fair value levels	213.0	185.0
Pension Plans | United Kingdom | Fixed income: Pooled UK government index-linked securities
Pension and Other Postretirement Benefits
Total assets at fair value by fair value levels	31.0	28.0
Pension Plans | United Kingdom | Fixed income: Pooled fixed income funds
Pension and Other Postretirement Benefits
Total assets at fair value by fair value levels	122.0	114.0
Pension Plans | United Kingdom | Pooled property funds
Pension and Other Postretirement Benefits
Total assets at fair value by fair value levels	43.0	36.0
Pension Plans | United Kingdom | NAV
Pension and Other Postretirement Benefits
Total assets at fair value by fair value levels	43.0	36.0
Pension Plans | United Kingdom | Quoted Prices in Active Markets (Level 1)
Pension and Other Postretirement Benefits
Total assets at fair value by fair value levels	5.0	3.0
Pension Plans | United Kingdom | Quoted Prices in Active Markets (Level 1) | Cash and cash equivalents
Pension and Other Postretirement Benefits
Total assets	5.0	3.0
Pension Plans | United Kingdom | Significant Other Observable Inputs (Level 2)
Pension and Other Postretirement Benefits
Total assets at fair value by fair value levels	366.0	327.0
Pension Plans | United Kingdom | Significant Other Observable Inputs (Level 2) | Pooled Target Return Funds
Pension and Other Postretirement Benefits
Total assets at fair value by fair value levels	213.0	185.0
Pension Plans | United Kingdom | Significant Other Observable Inputs (Level 2) | Fixed income: Pooled UK government index-linked securities
Pension and Other Postretirement Benefits
Total assets at fair value by fair value levels	31.0	28.0
Pension Plans | United Kingdom | Significant Other Observable Inputs (Level 2) | Fixed income: Pooled fixed income funds
Pension and Other Postretirement Benefits
Total assets at fair value by fair value levels	$ 122.0	$ 114.0
United Kingdom Terra | United Kingdom
Pension and Other Postretirement Benefits
Defined Benefit Plan, Target Plan Asset Allocations, Actively Managed Return Funds	55.00%