CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
OPERATING ACTIVITIES
Net income	$ 172,030	$ 84,342
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	63,690	58,709
Amortization of intangibles	6,463	1,927
Share-based compensation expense	6,641	5,678
Provision for losses on accounts receivable	3,583	(334)
Change in deferred income taxes	(6,371)	(7,612)
Gain on sale of property and equipment	(4,073)	(8,408)
Gain on sale of subsidiary	(402)	(6,923)
Changes in operating assets and liabilities:
Receivables	(87,092)	(37,745)
Prepaid expenses	7,477	1,419
Other assets	72	25
Income taxes	4,211	12,275
Operating right-of-use assets and lease liabilities, net	114	761
Accounts payable, accrued expenses, and other liabilities	18,280	41,786
NET CASH PROVIDED BY OPERATING ACTIVITIES	184,623	145,900
INVESTING ACTIVITIES
Purchases of property, plant and equipment, net of financings	(49,682)	(25,395)
Proceeds from sale of property and equipment	9,115	10,864
Proceeds from sale of subsidiary	475	9,013
Purchases of short-term investments	(64,330)	(43,690)
Proceeds from sale of short-term investments	35,840	49,165
Capitalization of internally developed software	(8,541)	(9,477)
Business acquisitions, net of cash acquired	2,279
NET CASH USED IN INVESTING ACTIVITIES	(74,844)	(9,520)
FINANCING ACTIVITIES
Borrowings under credit facilities	58,000
Proceeds from notes payable	7,280
Payments on long-term debt	(84,905)	(54,643)
Net change in book overdrafts	6,085	(922)
Deferred financing costs		(189)
Payment of common stock dividends	(4,927)	(4,095)
Purchases of treasury stock	(31,237)	(8,100)
Payments for tax withheld on share-based compensation	(9,637)	(9,766)
NET CASH USED IN FINANCING ACTIVITIES	(59,341)	(77,715)
NET INCREASE IN CASH AND CASH EQUIVALENTS	50,438	58,665
Cash and cash equivalents at beginning of period	76,620	303,954
CASH AND CASH EQUIVALENTS AT END OF PERIOD	127,058	362,619
NONCASH INVESTING ACTIVITIES
Equipment financed	19,498	8,138
Accruals for equipment received	7,574	5,984
Lease liabilities arising from obtaining right-of-use assets	$ 30,210	$ 6,051