Short-Term Debt - Additional Information (Detail) - USD ($)			6 Months Ended	12 Months Ended
	Jul. 14, 2020	Feb. 06, 2020	Jun. 30, 2020	Dec. 31, 2019
Line Of Credit Facility [Line Items]
Weighted-average interest rate			0.83%	2.56%
Line of credit facility maximum borrowing capacity			$ 850,000,000	$ 550,000,000
Borrowings Outstanding			494,000,000	348,000,000
3-year Accounts Receivable Facility [Member]
Line Of Credit Facility [Line Items]
Line of credit facility maximum borrowing capacity			150,000,000	150,000,000
Borrowings Outstanding			$ 0	$ 53,000,000
Credit facility maturity date			Mar. 22, 2021	Mar. 22, 2021
3-year Accounts Receivable Facility [Member] | Subsequent Event [Member]
Line Of Credit Facility [Line Items]
Credit facility amendment date	Jul. 14, 2020
Line of credit facility maximum borrowing capacity	$ 150,000,000
364-day Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Line of credit facility maximum borrowing capacity		$ 300,000,000
Credit facility maturity period		364 days
Credit facility maturity date		Feb. 04, 2021
Minimum [Member]
Line Of Credit Facility [Line Items]
Commitment fees, percentage			0.125%
Maximum [Member]
Line Of Credit Facility [Line Items]
Commitment fees, percentage			0.35%