Debt (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Schedule of Long-Term Debt

Debt.

December 31,	2020		2019
6.150% Notes, due 2020	$	—	$	1,000
5.400% Notes, due 2021(1)	361		1,250
5.870% Notes, due 2022	476		627
5.125% Notes, due 2024	1,250		1,250
6.875% Notes, due 2025	1,200		—
5.900% Notes, due 2027	625		625
6.750% Bonds, due 2028	300		300
5.950% Notes, due 2037	625		625
4.750% Iowa Finance Authority Loan, due 2042	250		250
Other(2)	(12)		13
	5,075		5,940
Less: amount due within one year	376		1,034
Total long-term debt	$	4,699	$	4,906

(1)Redeemed on January 15, 2021.

(2)Includes various financing arrangements related to subsidiaries, unamortized debt discounts and unamortized debt issuance costs related to outstanding notes and bonds listed in the table above.