Debt - Schedule of Current Availability on Debt and Cash (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Weighted average daily interest rate	1.10%	1.50%	3.10%
Weighted average daily borrowings	$ 109,000	$ 85,000	$ 253,000
Maximum borrowings outstanding at any month-end	727,000	257,000	485,000
Credit facility maximum borrowing capacity	4,119,000	3,946,000	3,470,000
Borrowings outstanding	172,000	184,000	51,000
Outstanding letters of credit	24,000	36,000	31,000
Current availability	3,923,000	3,726,000	3,388,000
Available term loans	250,000	500,000	0
Cash and cash equivalents	598,086	1,088,855	343,856	$ 447,046
Total liquidity	$ 4,771,000	$ 5,315,000	$ 3,732,000