Debt - Summary of Debt (Parenthetical) (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Feb. 16, 2021
5.125% Senior Secured Notes due 2023 | Senior notes
Debt Instrument [Line Items]
Interest rate		5.125%	5.125%
Debt instrument maturity year		2023
4.000% Notes due 2027 | Senior notes
Debt Instrument [Line Items]
Interest rate	4.00%	4.00%
Debt instrument maturity year	2027	2027
7.950% Debentures due 2025 | Unsecured debt
Debt Instrument [Line Items]
Interest rate	7.95%	7.95%
Debt instrument maturity year	2025	2025
8.375% Debentures due 2027 | Unsecured debt
Debt Instrument [Line Items]
Interest rate	8.375%	8.375%
Debt instrument maturity year	2027	2027