Accounts Payable, Accrued Liabilities, and Other Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Refundable entrance fees	$ 296,278	$ 317,444
Accrued construction costs	150,204	95,293
Accrued interest	31,313	78,735
Other accounts payable and accrued liabilities	252,144	269,145
Accounts payable, accrued liabilities, and other liabilities	729,939	760,617
Unamortized nonrefundable entrance fee	$ 491,000	$ 484,000