Debt and Other Financing Arrangements - Schedule of Debt and Other Financing Arrangements (Parenthetical) (Detail)	1 Months Ended		12 Months Ended
	Dec. 31, 2020	Apr. 30, 2018	Dec. 31, 2020	Dec. 31, 2019
Due from 2022 to 2040 [Member] | Industrial Revenue Bonds [Member]
Debt Instrument [Line Items]
Debt instrument - maturity year - start			2022
Debt instrument - maturity year - end			2040
Due from 2022 to 2040 [Member] | Industrial Revenue Bonds [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	0.16%		0.16%	1.61%
Due from 2022 to 2040 [Member] | Industrial Revenue Bonds [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	0.19%		0.19%	1.82%
Notes, 4.125%, due 2022 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	4.125%		4.125%
Debt instrument - maturity year			2022
Notes, 4.000%, due 2023 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	4.00%		4.00%
Debt instrument - maturity year			2023
Notes, 2.000%, due 2025 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	2.00%		2.00%
Debt instrument - maturity year			2025
Notes, 3.950%, due 2028 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	3.95%	3.95%	3.95%
Debt instrument - maturity year		2028	2028
Notes, 2.700%, due 2030 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	2.70%		2.70%
Debt instrument - maturity year			2030
Notes, 6.400%, due 2037 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	6.40%		6.40%
Debt instrument - maturity year			2037
Notes, 5.200%, due 2043 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	5.20%		5.20%
Debt instrument - maturity year			2043
Notes, 4.400%, due 2048 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	4.40%	4.40%	4.40%
Debt instrument - maturity year		2048	2048
Notes, 2.979%, due 2055 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	2.979%		2.979%
Debt instrument - maturity year	2055		2055