Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
OPERATING ACTIVITIES
Net income	$ 93,681	$ 34,477
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	47,620	52,977
Deferred income taxes	(12,709)	(5,369)
Stock-based compensation	343	800
Gain on disposal of property and equipment	(85,970)	(12,088)
Changes in certain working capital items:
Trade receivables	(10,600)	(3,713)
Prepaid expenses and other current assets	(778)	2,073
Accounts payable, accrued liabilities, and accrued expenses	8,521	(5,502)
Accrued income taxes	18,400	(880)
Net cash provided by operating activities	58,508	62,775
INVESTING ACTIVITIES
Proceeds from sale of property and equipment	129,820	56,030
Purchases of property and equipment	(50,563)	(47,585)
Payments to Acquire Businesses, Net of Cash Acquired	(122,049)	0
Change in other assets	(9)	(174)
Net cash provided by (used in) investing activities	(42,801)	8,271
FINANCING ACTIVITIES
Payments of cash dividends	(1,579)	(3,198)
Shares withheld for employee taxes related to stock-based compensation	(66)	(110)
Repayments on finance leases and debt	(1,113)	0
Repurchases of common stock	0	(15,022)
Net cash used in financing activities	(2,758)	(18,330)
Net increase in cash, cash equivalents and restricted cash	12,949	52,716
CASH, CASH EQUIVALENTS AND RESTRICTED CASH
Beginning of period	173,767	131,140
Ending Period	186,716	183,856
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Interest Paid, Excluding Capitalized Interest, Operating Activities	159	0
Cash paid during the period for income taxes, net of refunds	28,310	17,715
Noncash investing and financing activities:
Purchased property and equipment in accounts payable	1,033	6,415
Sold revenue equipment and property in other current assets	3,084	1,516
Common stock dividends declared in accounts payable	1,579	0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	4,653	0
Right-of-use assets obtained in exchange for operating lease liabilities through acquisitions	24,143	0
RECONCILIATION OF CASH, CASH EQUIVALENTS AND RESTRICTED CASH
Cash and Cash Equivalents, at Carrying Value	171,879	167,241
Restricted Cash and Investments, Current	897	1,007
Restricted Cash and Cash Equivalents, Noncurrent	13,940	15,608
Ending Period	$ 186,716	$ 183,856