Income Taxes (Narrative) (Details) - USD ($) $ in Thousands			12 Months Ended
	Dec. 23, 2017	Dec. 22, 2017	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Examination [Line Items]
Effective tax rate	21.00%	35.00%	21.00%	21.00%	21.00%
Tax valuation allowance			$ 0	$ 0
Reserves for uncetain tax positions			0	0
Income tax expense impacted by the benefit from Federal Energy Credits			8,549	17,256	$ 2,426
Federal income tax credit for each home meets the statute			2
Income tax expense			$ 64,083	$ 19,641	$ 32,075
Maximum [Member] | Federal [Member]
Income Tax Examination [Line Items]
Income tax year under examination			2020
Minimum [Member] | Federal [Member]
Income Tax Examination [Line Items]
Income tax year under examination			2015