Summary of Significant Accounting Policies (Narrative) (Details) $ in Thousands, shares in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2016 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) shares	Jan. 01, 2019 USD ($)	Jan. 01, 2018 USD ($)	Mar. 31, 2016 USD ($) home lot
Intangible asset useful life		20 years
Unfunded settlements		$ 40,900	$ 80,300
Restricted Cash and Cash Equivalents		23,612	33,485
Intangible assets, acquired cost (gross)		277,000	277,000
Intangible assets, accumulated amortization		190,200	176,400
Intangible assets amortization expense		13,800	13,800	$ 13,800
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months		13,800
Future Amortization Expense, Year Two		13,800
Future Amortization Expense, Year Three		10,400
Future Amortization Expense, Year Four		5,700
Property and equipment, net		92,935	70,706
Property and equipment, accumulated depreciation		209,300	206,500
Depreciation Expense		35,600	37,200	40,200
Advertising Expense		51,000	45,000	50,700
Employee benefit plan company contributions		$ 17,900	15,700	$ 14,600
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares				1.8
Number of VIEs requiring consolidation		0
Residential mortgage loans available-for-sale		$ 461,354	570,600
Residential mortgage loans available-for-sale aggregate outstanding principal balance		444,200	553,500
Net gain (loss) from change in fair value		700	(2,200)
Net gains from the sale of mortgages		111,300	110,900	$ 109,600
Loans held for investment, net		$ 8,900	11,200
Days past contractual term once loans no longer accrue interest income		90 days
Variability in future cash flows of derivative instruments in days		60 days
Contract liabilities		$ 254,600	250,800
Revenue from Contract with Customer, Excluding Assessed Tax		10,188,331	8,577,686	7,676,530
Capitalized contract costs		$ 30,800
Contract assets						$ 27,700
Minimum | Office Furniture and Equipment [Member]
Property and equipment, useful life		3 years
Minimum | Software and Hardware [Member]
Property and equipment, useful life		3 years
Minimum | Model Park Improvements and Furnishings [Member]
Property and equipment, useful life		1 year
Maximum | Office Furniture and Equipment [Member]
Property and equipment, useful life		10 years
Maximum | Software and Hardware [Member]
Property and equipment, useful life		5 years
Maximum | Model Park Improvements and Furnishings [Member]
Property and equipment, useful life		5 years
Financial Services [Member]
Interest income on mortgage loans		$ 11,300	9,500	$ 8,000
Interest Rate Lock Commitments [Member]
Derivative, notional amount		285,000	210,900
Forward Contracts [Member]
Derivative, notional amount		511,000	522,000
Whole Loan Commitments [Member]
Derivative, notional amount		$ 187,800	$ 203,100
JW Homes (Wieland) [Member] | JW Homes (Wieland) [Member]
Number of Units in Real Estate Property | lot							317
JW Homes (Wieland) [Member]
Business Combination, Consideration Transferred	$ 430,500
Number of Units in Real Estate Property | lot							7,000
Goodwill							$ 40,400
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net							$ 18,000
JW Homes (Wieland) [Member] | JW Homes (Wieland) [Member]
Number of Units in Real Estate Property | home							375
JW Homes (Wieland) [Member] | Land Option Contracts [Member]
Number of Units in Real Estate Property | lot							1,300
Restricted stock [Member]
Share-based compensation vesting period		3 years
Land Sales [Member]
Revenue from Contract with Customer, Excluding Assessed Tax		$ 31,400
Pro Forma [Member] | Accounting Standards Update 2016-02 [Member]
Operating Lease, Liability					$ 80,000