Acquisitions and Divestitures (Details 5) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Income tax provision (benefit)	$ 0.2	$ 0.1	$ 0	$ (0.7)
Net income (loss) from discontinued operations	0.6	0.3	0.1	(1.2)
Ready-Mix Concrete Operations
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Revenues	0	0	0	31.6
Income (loss) from discontinued operations before income taxes	0.8	0.4	0.1	(1.9)
Income tax provision (benefit)	0.2	0.1	0	(0.7)
Net income (loss) from discontinued operations	$ 0.6	$ 0.3	$ 0.1	$ (1.2)