Inventory (Summary of Interests in Land Option Agreements) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Deposits and Pre-acquisition Costs	$ 199,982	$ 195,436
Remaining Purchase Price	1,940,295	2,102,563
Land options with VIEs
Variable Interest Entity [Line Items]
Deposits and Pre-acquisition Costs	68,691	68,527
Remaining Purchase Price	676,923	849,901
Other land options
Variable Interest Entity [Line Items]
Deposits and Pre-acquisition Costs	131,291	126,909
Remaining Purchase Price	$ 1,263,372	$ 1,252,662