Commitments and Contingencies Commitments and Contingencies (Land and Lot Option Contracts) (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2018	$ 137,548
2019	47,588
2020	16,092
2021	5,765
Total expected purchase payments	$ 206,993

Land and lots under Purchase Options, Expected Purchase Payments, Next Twelve Months

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Land and lots under Purchase Options, Expected Purchase Payments, Total

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Land and lots under Purchase Options, Expected Purchase Payments, Year Four

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Land and lots under Purchase Options, Expected Purchase Payments, Year Three

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Land and lots under Purchase Options, Expected Purchase Payments, Year Two

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