Inventory (Summary of Interests in Land Option Agreements) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Deposits and Pre-acquisition Costs	$ 319,820	$ 291,864
Remaining Purchase Price	4,304,720	3,773,568
Land options with VIEs
Variable Interest Entity [Line Items]
Deposits and Pre-acquisition Costs	142,771	126,900
Remaining Purchase Price	1,844,131	1,586,551
Other land options
Variable Interest Entity [Line Items]
Deposits and Pre-acquisition Costs	177,049	164,964
Remaining Purchase Price	$ 2,460,589	$ 2,187,017