Debt - LT Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt	$ 2,244,443	$ 2,097,940
Debt Instrument, Face Amount	500
Accounts receivable, net	11,123,946	9,205,343
Long-term Debt, Maturities, Repayments of Principal in Year Two	299,558
Long-term Debt, Maturities, Repayments of Principal in Year Three	497,317
Long-term Debt, Maturities, Repayments of Principal in Year Four	347,699
Long-term Debt, Maturities, Repayments of Principal in Year Five	0
Long-term Debt, Maturities, Repayments of Principal after Year Five	1,099,869
Investment Income, Interest and Dividend	14,722	22,568	$ 54,815
Interest Paid, Including Capitalized Interest, Operating and Investing Activities	113,090	138,303	$ 209,512
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum Borrowing Capacity	$ 2,000,000
Debt Instrument, Interest Rate, Effective Percentage	1.15%
Facility Fee	0.175%
Debt Instrument, Basis Spread on Variable Rate	1.08%
North American Asset Securitization Program [Member]
Debt Instrument [Line Items]
Maximum Borrowing Capacity	$ 1,250,000
Debt Instrument, Interest Rate, Effective Percentage	0.53%
Facility Fee	0.40%
Debt Instrument, Basis Spread on Variable Rate	0.45%
Accounts receivable, net	$ 2,735,145	2,207,700
3.50% Notes, Due 2022 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 0	348,918
Debt Instrument, Interest Rate, Stated Percentage	3.50%
4.50% Notes, Due 2023 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 299,283	298,701
Debt Instrument, Fair Value	$ 309,000	321,500
Debt Instrument, Interest Rate, Stated Percentage	4.50%
3.25% Notes, Due 2024 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 497,060	496,034
Debt Instrument, Fair Value	$ 522,000	540,500
Debt Instrument, Interest Rate, Stated Percentage	3.25%
4.00% Notes, Due 2025 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 347,657	346,999
Debt Instrument, Fair Value	$ 374,000	383,000
Debt Instrument, Interest Rate, Stated Percentage	4.00%
7.50% Senior Debentures, Due 2027 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 110,021	109,939
Debt Instrument, Fair Value	$ 136,000	140,000
Debt Instrument, Interest Rate, Stated Percentage	7.50%
3.875% Notes, Due 2028 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 495,823	495,223
Debt Instrument, Fair Value	$ 542,500	564,000
Debt Instrument, Interest Rate, Stated Percentage	3.875%
Other obligations with various interest rates and due dates [Member]
Debt Instrument [Line Items]
Other Notes Payable, Noncurrent	$ 577	2,126
Notes Due in 2032 - 2.95%
Debt Instrument [Line Items]
Long-term debt	494,022	0
Debt Instrument, Fair Value	$ 504,500	$ 0
Debt Instrument, Interest Rate, Stated Percentage	2.95%