Inventory (Summary of Interests in Land Option Agreements) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Variable Interest Entity [Line Items]
Deposits and Pre-acquisition Costs	$ 290,356	$ 299,437
Remaining Purchase Price	3,686,733	3,221,962
Land options with VIEs
Variable Interest Entity [Line Items]
Deposits and Pre-acquisition Costs	115,420	123,775
Remaining Purchase Price	1,497,721	1,466,585
Other land options
Variable Interest Entity [Line Items]
Deposits and Pre-acquisition Costs	174,936	175,662
Remaining Purchase Price	$ 2,189,012	$ 1,755,377