Summary of Significant Accounting Policies - Accounting policies (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
Decrease in cash used in operating activities			$ 78,225	$ 35,950
Revenues	$ 203,560	$ 201,194	355,568	356,742
Property and equipment	39,948		39,948			$ 32,664
Accounting Standards Update 2016-15 [Member]
Decrease in cash used in operating activities				200
Accounting Standards Update 2014-09 [Member]
Property and equipment					$ 5,300
Adjustment to retained earnings					$ 1,800
Homebuilding
Revenues	198,656	$ 196,884	343,801	$ 345,544
Homebuilding | Accounting Standards Update 2014-09 [Member]
Revenues	$ 4,500		$ 8,700