RiverTown Impact Fees (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Real estate sale
Revenues		$ 160,555	$ 127,085	$ 110,276
Mattamy - RiverTown sale
Real estate sale
Impact fees received	$ 23,100	1,700	1,300	23,700
Residential | Operating Segments
Real estate sale
Revenues		$ 74,715	$ 41,586	43,266
Residential | Operating Segments | Real estate - Impact fees | Mattamy - RiverTown sale
Real estate sale
Revenues				$ 23,100