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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Fair Value of Assets and Liabilities - Financial Instruments (Details) - USD ($) $ in Thousands	Jan. 20, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value of Financial Instruments
Senior notes		$ 2,017,379	$ 2,357,497
Mortgage notes payable		309,946	335,241
Unamortized debt premiums, discounts and issuance costs		(45,756)	(56,372)
Long-term debt		$ 2,340,453	3,254,890
Senior unsecured notes, 3.750% interest rate, due in 2019
Fair Value of Financial Instruments
Interest rate (as a percent)		3.75%
Senior unsecured notes, 3.60% interest rate, due in 2020
Fair Value of Financial Instruments
Interest rate (as a percent)		3.60%
Senior unsecured notes, 4.00% interest rate, due in 2022
Fair Value of Financial Instruments
Interest rate (as a percent)		4.00%
Senior unsecured notes, 4.15% interest rate, due in 2022
Fair Value of Financial Instruments
Interest rate (as a percent)		4.15%
Senior unsecured notes, 4.25% interest rate, due in 2024
Fair Value of Financial Instruments
Interest rate (as a percent)		4.25%
Senior unsecured notes, 4.50% interest rate, due in 2025
Fair Value of Financial Instruments
Interest rate (as a percent)		4.50%
Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Interest rate (as a percent)		5.875%
Carrying Amount
Fair Value of Financial Instruments
Mortgage notes payable		$ 323,074	335,241
Fair value of debt		2,340,453	2,692,738
Carrying Amount \| Senior unsecured notes, 3.750% interest rate, due in 2019
Fair Value of Financial Instruments
Senior notes		0	349,239
Carrying Amount \| Senior unsecured notes, 3.60% interest rate, due in 2020
Fair Value of Financial Instruments
Senior notes		399,934	399,146
Carrying Amount \| Senior unsecured notes, 4.00% interest rate, due in 2022
Fair Value of Financial Instruments
Senior notes		297,657	296,735
Carrying Amount \| Senior unsecured notes, 4.15% interest rate, due in 2022
Fair Value of Financial Instruments
Senior notes		297,795	296,736
Carrying Amount \| Senior unsecured notes, 4.25% interest rate, due in 2024
Fair Value of Financial Instruments
Senior notes		340,018	337,736
Carrying Amount \| Senior unsecured notes, 4.50% interest rate, due in 2025
Fair Value of Financial Instruments
Senior notes		381,055	377,329
Carrying Amount \| Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Senior notes		300,920	300,576
Fair Value
Fair Value of Financial Instruments
Mortgage notes payable		331,675	336,365
Fair value of debt		2,451,248	2,665,550
Fair Value \| Senior unsecured notes, 3.750% interest rate, due in 2019
Fair Value of Financial Instruments
Senior notes		0	348,903
Fair Value \| Senior unsecured notes, 3.60% interest rate, due in 2020
Fair Value of Financial Instruments
Senior notes		400,048	399,146
Fair Value \| Senior unsecured notes, 4.00% interest rate, due in 2022
Fair Value of Financial Instruments
Senior notes		306,096	295,047
Fair Value \| Senior unsecured notes, 4.15% interest rate, due in 2022
Fair Value of Financial Instruments
Senior notes		307,221	296,736
Fair Value \| Senior unsecured notes, 4.25% interest rate, due in 2024
Fair Value of Financial Instruments
Senior notes		364,602	337,736
Fair Value \| Senior unsecured notes, 4.50% interest rate, due in 2025
Fair Value of Financial Instruments
Senior notes		419,578	377,329
Fair Value \| Senior unsecured notes, 5.875% interest rate, due in 2046
Fair Value of Financial Instruments
Senior notes		322,028	274,288
Senior Notes and Mortgages
Fair Value of Financial Instruments
Unamortized debt premiums, discounts and issuance costs		$ (45,756)	$ (55,524)
Senior Unsecured Notes \| Senior unsecured notes, 3.60% interest rate, due in 2020
Fair Value of Financial Instruments
Interest rate (as a percent)		3.60%
Senior Unsecured Notes \| Senior unsecured notes, 4.00% interest rate, due in 2022
Fair Value of Financial Instruments
Interest rate (as a percent)		4.00%
Senior Unsecured Notes \| Senior unsecured notes, 4.15% interest rate, due in 2022
Fair Value of Financial Instruments
Interest rate (as a percent)		4.15%
Senior Unsecured Notes \| Senior unsecured notes, 4.25% interest rate, due in 2024
Fair Value of Financial Instruments
Interest rate (as a percent)		4.25%
Senior Unsecured Notes \| Senior unsecured notes, 4.50% interest rate, due in 2025
Fair Value of Financial Instruments
Interest rate (as a percent)		4.50%
Disposal Group, Held-for-sale \| Mortgages
Fair Value of Financial Instruments
Long-term debt		$ 13,128
Unamortized debt issuance expense		$ 38
Subsequent Event \| Senior Unsecured Notes \| Senior unsecured notes, 3.60% interest rate, due in 2020
Fair Value of Financial Instruments
Interest rate (as a percent)	3.60%
Repayments of debt	$ 400,000