Inventory (Summary of Interests in Land Option Agreements) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Deposits and Pre-acquisition Costs	$ 255,430	$ 218,568
Remaining Purchase Price	2,803,409	2,602,410
Land options with VIEs
Variable Interest Entity [Line Items]
Deposits and Pre-acquisition Costs	100,523	90,717
Remaining Purchase Price	1,109,963	1,079,507
Other land options
Variable Interest Entity [Line Items]
Deposits and Pre-acquisition Costs	154,907	127,851
Remaining Purchase Price	$ 1,693,446	$ 1,522,903