Summary of Significant Accounting Policies (Narrative) (Details) shares in Millions	1 Months Ended		12 Months Ended
	Jan. 31, 2016 USD ($)	Aug. 31, 2014 USD ($)	Dec. 31, 2016 USD ($) shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($) home lot shares	Mar. 31, 2016 USD ($) home lot
Business Combination, Consideration Transferred		$ 82,400,000
Number of Units in Real Estate Property | lot					8,200
Intangible asset useful life			20 years
Sales Commissions and Fees			$ 268,300,000	$ 204,900,000	$ 193,600,000
Percentage_commisions_of_sales_reclass			3.60%	3.50%	3.40%
Unfunded settlements			$ 66,500,000	$ 27,500,000
Restricted Cash and Cash Equivalents			24,366,000	21,274,000
Intangible assets, acquired cost (gross)			277,000,000	259,000,000
Intangible assets, accumulated amortization			162,600,000	148,800,000
Intangible assets amortization expense			13,800,000	12,900,000	$ 13,033,000
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months			13,800,000
Future Amortization Expense, Year Two			13,800,000
Future Amortization Expense, Year Three			13,800,000
Future Amortization Expense, Year Four			13,800,000
Future Amortization Expense, Year Five			13,800,000
Property and equipment, net			77,444,000	86,312,000
Property and equipment, accumulated depreciation			192,900,000	185,800,000
Depreciation Expense			40,200,000	33,300,000	26,800,000
Advertising Expense			50,700,000	45,300,000	41,800,000
Employee benefit plan company contributions			$ 14,600,000	$ 12,600,000	$ 12,100,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares			1.8	3.9	6.6
Number of VIEs requiring consolidation			0
Residential mortgage loans available-for-sale			$ 539,496,000	$ 442,715,000
Residential mortgage loans available-for-sale aggregate outstanding principal balance			529,700,000	429,600,000
Net gain (loss) from change in fair value			2,800,000	(300,000)
Net gains from the sale of mortgages			109,600,000	80,800,000	$ 67,200,000
Loans held for investment, net			$ 8,400,000	7,600,000
Days past contractual term once loans no longer accrue interest income			90 days
Variability in future cash flows of derivative instruments in days			90 days
unrecognized tax benefits in equity share based payment			18600
Intangible asset impairment expense				0	0
Furniture and Fixtures [Member]
Property and equipment, useful life			2 years
Minimum [Member]
Period of Reimbursement of Payments on Loan Prepay in Days			90 days
Minimum [Member] | Equipment [Member]
Property and equipment, useful life			3 years
Maximum [Member]
Period of Reimbursement of Payments on Loan Prepay in Days			120 days
Maximum [Member] | Equipment [Member]
Property and equipment, useful life			10 years
Financial Services [Member]
Interest income on mortgage loans			$ 8,000,000	6,900,000	$ 7,200,000
Interest Rate Lock Commitments [Member]
Derivative, notional amount			273,900,000	208,200,000
Forward Contracts [Member]
Derivative, notional amount			610,000,000	525,000,000
Whole Loan Commitments [Member]
Derivative, notional amount			$ 157,600,000	$ 77,600,000
JW Homes (Wieland) [Member] | JW Homes (Wieland) [Member]
Number of Units in Real Estate Property | lot						317
Dominion [Member] | Dominion [Member]
Number of Units in Real Estate Property | lot					622
JW Homes (Wieland) [Member]
Business Combination, Consideration Transferred	$ 430,500,000
Number of Units in Real Estate Property | lot						7,000
Goodwill						$ 40,400,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net						$ 18,000,000
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
Dominion [Member] | Land Option Contracts [Member]
Number of Units in Real Estate Property | lot					900
Dominion [Member] | Dominion [Member]
Number of Units in Real Estate Property | home					400
Restricted stock [Member]
Share-based compensation vesting period			3 years