Acquisition of RSI Communities - Summary of Preliminary Amounts for Acquired Assets and Liabilities Recorded at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Mar. 09, 2018
Assets Acquired
Goodwill	$ 123,695	$ 123,695
RSI Communities
Assets Acquired
Real estate inventories			$ 434,628
Goodwill			56,793
Other			7,771
Total Assets			499,192
Liabilities Assumed
Accounts payable			9,315
Accrued expenses			8,244
Notes payable			2,305
Total liabilities			19,864
Net assets acquired			$ 479,328