Short-Term Debt - Credit Facilities and Related Borrowings (Parenthetical) (Detail)	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
5-year Facility [Member]
Line Of Credit Facility [Line Items]
Credit facility maturity date	Mar. 22, 2022	Mar. 22, 2022
3-year Accounts Receivable Facility [Member]
Line Of Credit Facility [Line Items]
Credit facility maturity date	Mar. 22, 2021	Mar. 22, 2021
1-year Term Facility [Member]
Line Of Credit Facility [Line Items]
Credit facility maturity date	Feb. 04, 2021	Feb. 04, 2021