Fair Value (Assets and Liabilities Not Measured at Fair Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Assets:
Cash and Restricted cash	$ 1,174,328	$ 1,242,997	$ 1,238,713	$ 620,135
Liabilities:
Variable-rate debt	1,767,218	1,945,344
Allowance for accounts receivable	32,300	33,000
Notes receivable
Liabilities:
Allowance for notes receivable	100	200
Fair Value Hierarchy Level 1 | Carrying Amount
Assets:
Cash and Restricted cash	1,174,328	1,242,997
Fair Value Hierarchy Level 1 | Estimated Fair Value
Assets:
Cash and Restricted cash	1,174,328	1,242,997
Fair Value Hierarchy Level 3 | Carrying Amount
Assets:
Accounts receivable, net	70,990	7,437
Notes receivable, net	1,300	622
Fair Value Hierarchy Level 3 | Estimated Fair Value
Assets:
Accounts receivable, net	70,990	7,437
Notes receivable, net	1,300	622
Fair Value Hierarchy Level 2 | Carrying Amount
Liabilities:
Fixed-rate debt	2,672,304	2,374,822
Variable-rate debt	1,767,218	1,945,344
Fair Value Hierarchy Level 2 | Estimated Fair Value
Liabilities:
Fixed-rate debt	2,681,014	2,461,155
Variable-rate debt	$ 1,767,218	$ 1,945,344