Fair Value Measurements - Schedule of Assets Measured at Fair Value on a Recurring Basis (Details) - Fair Value Recurring Basis - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets:
Restricted cash and investments	$ 43,000	$ 42,000
Marketable securities	61,000	35,000
Total assets at fair value	104,000	77,000
Liabilities, Fair Value Disclosure [Abstract]
Other liabilities related to restricted investments	4,000
Total liabilities at fair value	693,000
5% Convertible notes
Liabilities, Fair Value Disclosure [Abstract]
Derivative instruments	575,000
Interest Rate Swaps and FX Forward
Liabilities, Fair Value Disclosure [Abstract]
Derivative instruments	114,000
Fair Value, Inputs, Level 1
Assets:
Restricted cash and investments	8,000	11,000
Marketable securities	31,000	27,000
Total assets at fair value	39,000	38,000
Liabilities, Fair Value Disclosure [Abstract]
Other liabilities related to restricted investments	0
Total liabilities at fair value	0
Fair Value, Inputs, Level 1 | 5% Convertible notes
Liabilities, Fair Value Disclosure [Abstract]
Derivative instruments	0
Fair Value, Inputs, Level 1 | Interest Rate Swaps and FX Forward
Liabilities, Fair Value Disclosure [Abstract]
Derivative instruments	0
Fair Value, Inputs, Level 2
Assets:
Restricted cash and investments	3,000	2,000
Marketable securities	12,000	8,000
Total assets at fair value	15,000	10,000
Liabilities, Fair Value Disclosure [Abstract]
Other liabilities related to restricted investments	0
Total liabilities at fair value	689,000
Fair Value, Inputs, Level 2 | 5% Convertible notes
Liabilities, Fair Value Disclosure [Abstract]
Derivative instruments	575,000
Fair Value, Inputs, Level 2 | Interest Rate Swaps and FX Forward
Liabilities, Fair Value Disclosure [Abstract]
Derivative instruments	114,000
Fair Value, Inputs, Level 3
Assets:
Restricted cash and investments	50,000	29,000
Marketable securities	0	0
Total assets at fair value	50,000	$ 29,000
Liabilities, Fair Value Disclosure [Abstract]
Other liabilities related to restricted investments	4,000
Total liabilities at fair value	4,000
Fair Value, Inputs, Level 3 | 5% Convertible notes
Liabilities, Fair Value Disclosure [Abstract]
Derivative instruments	0
Fair Value, Inputs, Level 3 | Interest Rate Swaps and FX Forward
Liabilities, Fair Value Disclosure [Abstract]
Derivative instruments	$ 0