Inventory Other Inventory Items - Homes under construction not subject to a sale contract (Details) $ in Millions	Dec. 31, 2016 USD ($) homes	Dec. 31, 2015 USD ($) homes
Other Inventory, Gross [Abstract]
Number of Speculative Homes | homes	996	872
Speculative Homes Carrying Value | $	$ 199.4	$ 184.3