Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
OPERATING ACTIVITIES
Net income	$ 92,904	$ 114,891
Adjustments to reconcile net income to net cash (used for) provided by operating activities:
Depreciation and amortization	23,878	24,380
Provision for credit losses	2,813	(6,637)
Stock-based compensation	22,673	15,607
Deferred income taxes	(6,805)	(10,272)
Excess tax benefit on stock-based compensation	(1,570)	(7,011)
Other operating activities	5,596	942
Changes in operating elements:
Receivables	(225,402)	326,244
Contract assets	(45,574)	66,124
Prepaid expenses and other	(11,409)	433
Increase (Decrease) in Right of Use Asset	(13,933)	13,841
Accounts payable and outstanding checks	84,966	(90,724)
Accrued compensation	(23,407)	(134,795)
Accrued transportation expense	38,106	(53,882)
Accrued income taxes	3,619	(40)
Other accrued liabilities	5,446	8,169
Increase (Decrease) in Operating Lease Liability	14,347	(14,003)
Other assets and liabilities	429	1,277
Net cash (used for) provided by operating activities	(33,323)	254,544
INVESTING ACTIVITIES
Purchases of property and equipment	(8,620)	(11,371)
Purchases and development of software	(13,854)	(15,579)
Net cash used for investing activities	(22,474)	(26,950)
FINANCING ACTIVITIES
Proceeds from stock issued for employee benefit plans	5,405	19,673
Stock tendered for payment of withholding taxes	(16,130)	(20,048)
Repurchase of common stock	0	(31,182)
Cash dividends	(74,580)	(73,435)
Proceeds from short-term borrowings	912,000	739,000
Payments on short-term borrowings	(792,000)	(840,000)
Net cash provided by (used for) financing activities	34,695	(205,992)
Effect of exchange rates on cash and cash equivalents	(2,584)	76
Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Disposal Group, Including Discontinued Operations	(23,686)	21,678
Cash and cash equivalents, beginning of period	145,524	217,482
Cash and cash equivalents, end of period	$ 121,838	$ 239,160