Goodwill and Other Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Goodwill and Other Intangible Assets
Impairment of goodwill	$ 0
Goodwill	37.1	16.8
North
Goodwill and Other Intangible Assets
Goodwill	13.7
Southeast
Goodwill and Other Intangible Assets
Goodwill	8.1	8.1
Texas
Goodwill and Other Intangible Assets
Goodwill	6.6
West
Goodwill and Other Intangible Assets
Goodwill	$ 8.7	$ 8.7