Mortgages, Notes and Loans Payable, Net (Narrative) (Details)	1 Months Ended			3 Months Ended	9 Months Ended		12 Months Ended
	Oct. 31, 2021 USD ($)	Sep. 30, 2021 USD ($) extension_option	Apr. 30, 2021 USD ($)	Sep. 30, 2021 USD ($) extension_option	Sep. 30, 2021 USD ($) extension_option	Sep. 30, 2020 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Mortgages, notes and loans payable
Land, buildings and equipment and developments in progress pledged as collateral		$ 4,200,000,000		$ 4,200,000,000	$ 4,200,000,000
Repayments					1,758,772,000	$ 861,975,000
Special Improvement District bond transfers associated with land sales					8,484,000	$ 3,090,000
Increase in restricted cash					58,800,000
Reimbursement related to operating expenses				33,100,000
1201 Lake Robbins
Mortgages, notes and loans payable
Repayments					273,070,000
Term loan
Mortgages, notes and loans payable
Repayments					181,800,000
Outstanding borrowings		433,200,000		433,200,000	433,200,000
Term loan | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Mortgages, notes and loans payable
Repayments					62,500,000
Proceeds from sale of properties					69,800,000
Special Improvement District bonds
Mortgages, notes and loans payable
Special improvement district bond issued					45,400,000
Special Improvement District bond transfers associated with land sales					8,484,000
Construction Loans | Marlow development
Mortgages, notes and loans payable
Face amount			$ 82,600,000
Long-term debt outstanding		0		0	0
Term of extension option			1 year
Construction Loans | Marlow development | LIBOR
Mortgages, notes and loans payable
Interest rate margin			2.95%
Construction Loans | Starling at Bridgeland
Mortgages, notes and loans payable
Face amount			$ 42,700,000
Long-term debt outstanding		0		0	0
Term of extension option			1 year
Construction Loans | Starling at Bridgeland | Minimum
Mortgages, notes and loans payable
Interest rate			3.75%
Construction Loans | Starling at Bridgeland | LIBOR
Mortgages, notes and loans payable
Interest rate margin			2.75%
Construction Loans | 8770 New Trails
Mortgages, notes and loans payable
Face amount								$ 35,500,000		$ 35,500,000
Construction Loans | Tanager Echo Development
Mortgages, notes and loans payable
Face amount		$ 59,500,000		$ 59,500,000	$ 59,500,000
Term of extension option		1 year
Number of extension options | extension_option		2		2	2
Construction Loans | Tanager Echo Development | Subsequent Event
Mortgages, notes and loans payable
Derivative, cap interest rate	2.50%
Construction Loans | Tanager Echo Development | LIBOR
Mortgages, notes and loans payable
Interest rate margin		2.90%
Variable rate floor		0.10%
Construction Loans | Pavillion In Las Vegas Development
Mortgages, notes and loans payable
Face amount		$ 75,000,000		$ 75,000,000	$ 75,000,000
Term of extension option		1 year
Number of extension options | extension_option		2		2	2
Construction Loans | Pavillion In Las Vegas Development | LIBOR
Mortgages, notes and loans payable
Interest rate margin		3.80%
Variable rate floor		0.10%
Construction Loans | Outlet Collection At Riverwalk | Subsequent Event
Mortgages, notes and loans payable
Face amount	$ 27,200,000
Interest rate margin	3.00%
Term of extension option	1 year
Construction Loans | 1201 Lake Robbins | Subsequent Event
Mortgages, notes and loans payable
Face amount	$ 250,000,000
Derivative, cap interest rate	2.50%
Construction Loans | 1201 Lake Robbins | LIBOR | Subsequent Event
Mortgages, notes and loans payable
Interest rate margin	3.83%
Construction Loans | ‘A‘ali‘i Tower
Mortgages, notes and loans payable
Face amount		$ 229,600,000		$ 229,600,000	$ 229,600,000
$700 Million loan due 2023
Mortgages, notes and loans payable
Face amount							$ 700,000,000
Option to increase borrowing capacity							50,000,000
$700 Million loan due 2023 | Revolving Credit Facility
Mortgages, notes and loans payable
Face amount							85,000,000
$700 Million loan due 2023 | Term loan
Mortgages, notes and loans payable
Face amount		615,000,000		615,000,000	615,000,000		$ 615,000,000				$ 615,000,000
Repayments					181,800,000
$700 Million loan due 2023 | Line of credit | Revolving Credit Facility
Mortgages, notes and loans payable
Outstanding borrowings		0		0	0
Term loan
Mortgages, notes and loans payable
Repayments					181,800,000
The Woodlands and Bridgeland Credit Facility | Revolving Credit Facility
Mortgages, notes and loans payable
Face amount									$ 150,000,000
Repayments		100,000,000
Outstanding borrowings		$ 50,000,000		$ 50,000,000	$ 50,000,000
The Woodlands and Bridgeland Credit Facility | Term loan
Mortgages, notes and loans payable
Face amount									100,000,000
The Woodlands and Bridgeland Credit Facility | Line of credit
Mortgages, notes and loans payable
Facility amount									$ 250,000,000