Business Segments Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Revenue	$ 742,150	$ 653,345	$ 623,686	$ 481,109	$ 722,485	$ 567,842	$ 558,098	$ 437,857	$ 2,500,290	$ 2,286,282	$ 1,961,971
Operating income (loss):									187,089	163,161	138,659
Interest									21,375	20,484	18,874
Equity in income from joint venture arrangements									(311)	(312)	(539)
Acquisition and integration costs									0	1,700	0
Income before income taxes									166,025	141,289	120,324
Depreciation and amortization:									15,950	14,531	14,174
Northern Homebuilding [Member]
Segment Reporting Information [Line Items]
Revenue									1,027,291	933,119	742,577
Operating income (loss):									96,239	86,131	81,522
Interest									7,474	7,142	5,010
Depreciation and amortization:									2,944	2,448	2,069
Southern Homebuilding [Member]
Segment Reporting Information [Line Items]
Revenue									1,417,676	1,300,967	1,169,701
Operating income (loss):									115,082	95,912	72,396
Interest									10,250	10,073	11,107
Depreciation and amortization:									4,778	4,472	4,579
Financial Services Sector [Member]
Segment Reporting Information [Line Items]
Revenue									55,323	52,196	49,693
Operating income (loss):									27,350	27,482	27,288
Interest									3,651	3,269	2,757
Depreciation and amortization:									2,095	1,281	1,503
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Less: Corporate selling, general and administrative expenses									(51,582)	(46,364)	(42,547)
Depreciation and amortization:									$ 6,133	$ 6,330	$ 6,023