Business Combinations (Narrative) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
	Jun. 14, 2018	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Nov. 30, 2016
Business Combinations [Line Items]
Acquisition expense												$ 437
Revenues										$ 3,161,192	$ 2,535,911	2,147,413
Income before income tax expense		$ 121,164	$ 64,885	$ 50,103	$ 34,088	$ 53,968	$ 34,840	$ 20,830	$ 22,997	270,240	132,635	128,530
Equity in income of unconsolidated subsidiaries												14,849
Wade Jurney Homes [Member]
Business Combinations [Line Items]
Acquisition expense												400
Business combination, purchase price	$ 37,500
Ownership interest	50.00%												50.00%
Previously held equity interest	$ 35,625											35,600
Estimated discount for lack of control												1,900
Revenues												210,100
Income before income tax expense												(800)
Equity in income of unconsolidated subsidiaries												$ 7,200
Wade Jurney Homes [Member]
Business Combinations [Line Items]
Ownership subsidiary	100.00%
Cell Phone Tower Lease [Member] | Wade Jurney Homes [Member]
Business Combinations [Line Items]
Gain (loss) on assets impairment											800
Trade Names [Member] | Wade Jurney Homes [Member]
Business Combinations [Line Items]
Estimated fair value										$ 3,300
Amortization period										10 years
Impairment											3,300
Accumulated amortization						$ 500					500
Gain (loss) on assets impairment											$ (2,800)
Non-Compete Agreements [Member] | Wade Jurney Homes [Member]
Business Combinations [Line Items]
Estimated fair value										$ 300
Amortization period										2 years