Acquisitions and Divestitures (Details 7) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Benefit for income taxes	$ 0.0	$ 0.0	$ (0.8)
Net loss from discontinued operations	0.0	0.0	(0.8)
Ready-mix concrete operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues	0.0	0.0	31.6
Loss from discontinued operations before income taxes	0.0	0.0	(1.6)
Benefit for income taxes	0.0	0.0	(0.8)
Net loss from discontinued operations	$ 0.0	$ 0.0	$ (0.8)