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Pension and Savings Plans (Details 4) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 295.1	$ 281.2
Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	162.8	152.1
Level 2 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	301.0	301.0
Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	14.1	23.0
Equity Funds [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	119.9	107.1
Equity Funds [Member] | Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	119.9	107.1
Equity Funds [Member] | Level 2 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	0.0	0.0
Equity Funds [Member] | Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	0.0	0.0
International equity securities | Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period		0.0
U.S. debt securities
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	47.8	53.4
U.S. debt securities | Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	25.1	26.8
U.S. debt securities | Level 2 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	22.7	26.6
U.S. debt securities | Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	0.0
International debt securities
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	12.6	15.0
International debt securities | Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	0.0	0.0
International debt securities | Level 2 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	12.6	15.0
International debt securities | Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	0.0	0.0
Banks, Trust and Insurance, Equities [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	109.0	97.3
Corporate Debt Securities [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	265.7	259.4
Corporate Debt Securities [Member] | Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	0.0	0.0
Corporate Debt Securities [Member] | Level 2 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	265.7	259.4
Corporate Debt Securities [Member] | Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	0.0	0.0
Short-term investments
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	17.8	18.2
Short-term investments | Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	17.8	18.2
Short-term investments | Level 2 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	0.0	0.0
Short-term investments | Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	0.0	0.0
Interests in real estate
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	14.1	23.0
Interests in real estate | Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	0.0	0.0
Interests in real estate | Level 2 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	0.0	0.0
Interests in real estate | Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	14.1	23.0	$ 30.2
Private Equity Funds [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	186.1	183.9
Fair Value Pension Plan Assets [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	477.9	476.1
Pension Plans, Defined Benefit [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Fair value of plan assets at end of period	$ 773.0	$ 757.3	$ 839.8

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- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 30
-Section 35
-Paragraph 50
-URI http://asc.fasb.org/extlink&oid=49178875&loc=d3e12355-114930

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

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