Debt (Parenthetical) (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Feb. 24, 2021	Sep. 30, 2020
6.50% Exchangeable Senior Notes due 2026
Line Of Credit Facility [Line Items]
Stated interest rate	6.50%
6.00% Senior Notes due 2026
Line Of Credit Facility [Line Items]
Stated interest rate	6.00%	6.00%
5.875% Senior Notes due 2024
Line Of Credit Facility [Line Items]
Stated interest rate	5.875%	5.875%
5.125% Senior Notes due 2023
Line Of Credit Facility [Line Items]
Stated interest rate	5.125%	5.125%
5.875% Senior Notes due 2022
Line Of Credit Facility [Line Items]
Stated interest rate	5.875%	5.875%
Convertible Debt | 6.50% Exchangeable Senior Notes due 2026
Line Of Credit Facility [Line Items]
Stated interest rate	6.50%	6.50%	6.50%
Debt instrument maturity year	2026	2026
Senior Notes | 6.00% Senior Notes due 2026
Line Of Credit Facility [Line Items]
Stated interest rate	6.00%	6.00%
Debt instrument maturity year	2026	2026
Senior Notes | 5.875% Senior Notes due 2024
Line Of Credit Facility [Line Items]
Stated interest rate	5.875%	5.875%		5.875%
Debt instrument maturity year	2024	2024
Senior Notes | 5.125% Senior Notes due 2023
Line Of Credit Facility [Line Items]
Stated interest rate	5.125%	5.125%		5.125%
Debt instrument maturity year	2023	2023
Senior Notes | 5.875% Senior Notes due 2022
Line Of Credit Facility [Line Items]
Stated interest rate	5.875%	5.875%
Debt instrument maturity year	2022	2022