CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
OPERATING ACTIVITIES
Net income	$ 23,361	$ 1,902
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	29,387	28,032
Amortization of intangibles	967	981
Pension settlement expense		89
Share-based compensation expense	2,354	2,181
Provision for losses on accounts receivable	(96)	1,383
Change in deferred income taxes	(4,998)	(2,815)
Gain on sale of property and equipment	(8,635)	(2,130)
Changes in operating assets and liabilities:
Receivables	(22,568)	3,874
Prepaid expenses	(2,582)	(3,429)
Other assets	(164)	5,800
Income taxes	6,376	2,949
Operating right-of-use assets and lease liabilities, net	567	(138)
Accounts payable, accrued expenses, and other liabilities	(1,435)	(15,550)
NET CASH PROVIDED BY OPERATING ACTIVITIES	22,534	23,129
INVESTING ACTIVITIES
Purchases of property, plant and equipment, net of financings	(9,588)	(6,738)
Proceeds from sale of property and equipment	10,079	4,692
Purchases of short-term investments	(18,130)	(73,973)
Proceeds from sale of short-term investments	24,418	12,210
Capitalization of internally developed software	(5,705)	(3,342)
NET CASH PROVIDED BY (USED IN) INVESTING ACTIVITIES	1,074	(67,151)
FINANCING ACTIVITIES
Borrowings under credit facilities		180,000
Borrowings under accounts receivable securitization program		45,000
Payments on long-term debt	(17,387)	(14,598)
Net change in book overdrafts	(5,434)	(10,869)
Payment of common stock dividends	(2,037)	(2,033)
Purchases of treasury stock	(1,001)	(3,162)
Payments for tax withheld on share-based compensation	(161)	(60)
NET CASH PROVIDED BY (USED IN) FINANCING ACTIVITIES	(26,020)	194,278
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(2,412)	150,256
Cash and cash equivalents at beginning of period	303,954	201,909
CASH AND CASH EQUIVALENTS CASH AT END OF PERIOD	301,542	352,165
NONCASH INVESTING ACTIVITIES
Accruals for equipment received	233	39
Lease liabilities arising from obtaining right-of-use assets	$ 1,959	$ 10,370