Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Employee benefits, including post-retirement benefits	$ 15.4	$ 15.2
Trade and other receivables	2.9	4.1
Goodwill and intangibles	0.2	2.0
Self-insurance reserves	1.7	1.5
Other	6.1	4.0
Subtotal	26.3	26.8
Less: valuation allowance	0.0	0.0
Net deferred tax assets	26.3	26.8
Deferred tax liabilities:
Inventories	7.0	9.0
Property and equipment	36.2	27.2
Goodwill and intangibles	5.6	6.0
Other	1.8	1.6
Total deferred tax liabilities	50.6	43.8
Total net deferred tax liabilities	(24.3)	(17.0)
Net current deferred tax assets	4.6	1.6
Net non-current deferred tax liabilities	$ (28.9)	$ (18.6)