Pension and Savings Plans (Details 4) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	$ 152.1	$ 184.5
Level 2 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	582.2	625.1
Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	23.0	30.2
U.S. equity securities
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	147.3	190.3
U.S. equity securities | Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	107.1	141.7
U.S. equity securities | Level 2 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	40.2	48.6
U.S. equity securities | Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	0.0	0.0
International equity securities
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	57.1	69.8
International equity securities | Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	0.0	0.0
International equity securities | Level 2 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	57.1	69.8
International equity securities | Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	0.0	0.0
U.S. debt securities
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	53.4	54.4
U.S. debt securities | Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	26.8	25.3
U.S. debt securities | Level 2 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	26.6	29.1
U.S. debt securities | Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	0.0	0.0
International debt securities
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	15.0	23.5
International debt securities | Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	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
Total assets at fair value	15.0	23.5
International debt securities | Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	0.0	0.0
Corporate debt securities
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	443.1	447.8
Corporate debt securities | Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	0.0	0.0
Corporate debt securities | Level 2 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	443.1	447.8
Corporate debt securities | Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	0.0	0.0
Short-term investments
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	18.4	23.8
Short-term investments | Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	18.2	17.5
Short-term investments | Level 2 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	0.2	6.3
Short-term investments | Level 3 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	0.0	0.0
Interests in real estate
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	23.0	30.2
Interests in real estate | Level 1 [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	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
Total assets at fair value	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
Total assets at fair value	23.0	30.2	$ 29.9
Pension Plans, Defined Benefit [Member]
Fair value of assets in the Master Trust by category and by fair value valuation hierarchy
Total assets at fair value	$ 757.3	$ 839.8	$ 851.4