Homebuilding Senior Notes and Other Debts Payable (Narrative) (Details) - Homebuilding - USD ($)	1 Months Ended		9 Months Ended
	Oct. 08, 2019	Jun. 30, 2019	Aug. 31, 2019	Apr. 30, 2019	Mar. 31, 2019	Nov. 30, 2018
Debt Instrument [Line Items]
Guarantee by subsidiaries			$ 75,000,000
Surety Bond
Debt Instrument [Line Items]
Outstanding performance and surety bonds			2,900,000,000
Uncompleted site improvements amount			$ 1,400,000,000
Uncompleted site improvements percent			47.00%
Unsecured revolving credit facility
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 2,800,000,000
Accordion feature			400,000,000
Unsecured revolving credit facility | Credit Facility Due in April 2023
Debt Instrument [Line Items]
Maximum borrowing capacity					$ 2,300,000,000
Unsecured revolving credit facility | Credit Facility Due in April 2024
Debt Instrument [Line Items]
Maximum borrowing capacity				$ 2,400,000,000
Unsecured revolving credit facility | Credit Facility Due in June 2020
Debt Instrument [Line Items]
Maximum borrowing capacity			50,000,000
Letter of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity			305,000,000
Performance Letters of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity			500,000,000
Letters of credit outstanding			682,300,000			$ 598,400,000
Financial Letters of Credit
Debt Instrument [Line Items]
Letters of credit outstanding			180,800,000			165,400,000
Senior Notes
Debt Instrument [Line Items]
Debt issuance cost			$ 24,900,000			$ 31,200,000
Senior Notes | 4.500% senior notes due 2019
Debt Instrument [Line Items]
Repayments of principal		$ 500,000,000
Interest rate		4.50%	4.50%
Redemption price		100.00%
Subsequent Event | Unsecured revolving credit facility | Credit Facility Due in April 2024
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 2,500,000,000
Change in maximum borrowing capacity	$ 50,000,000