CONDENSED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net earnings (loss)	$ (321,700)	$ 91,897
Adjustments to reconcile net earnings (loss) to net cash provided by operations:
Depreciation and amortization	110,288	110,316
Provision (benefit) for deferred income taxes	(18,588)	26,007
Impairments and other charges	561,274	0
Amortization of unearned share-based compensation	8,652	7,907
Amortization of major maintenance costs	14,473	10,431
Other	3,513	(5,241)
Decrease in cash flows resulting from changes in operating assets and liabilities, net	(115,768)	(53,120)
Net cash provided by operating activities	242,144	188,197
Cash flows from investing activities:
Capital expenditures	(92,830)	(127,268)
Acquisitions of businesses and marine equipment	(342,247)	(252,840)
Proceeds from disposition of assets	4,918	23,364
Net cash used in investing activities	(430,159)	(356,744)
Cash flows from financing activities:
Borrowings (payments) on bank credit facilities, net	424,991	(313,805)
Borrowings on long-term debt	0	500,000
Payments on long-term debt	(150,000)	0
Payments of debt issue costs	0	(2,397)
Proceeds from exercise of stock options	353	1,903
Payments related to tax withholding for share-based compensation	(3,191)	(2,023)
Other	(404)	(410)
Net cash provided by financing activities	271,749	183,268
Increase in cash and cash equivalents	83,734	14,721
Cash and cash equivalents, beginning of year	24,737	7,800
Cash and cash equivalents, end of period	108,471	22,521
Cash paid (received) during the period:
Interest paid	26,265	29,271
Income taxes paid (refunded)	(37,704)	2,392
Operating cash outflow from operating leases	21,323	19,786
Non-cash investing activity:
Capital expenditures included in accounts payable	4,936	5,377
Right-of-use assets obtained in exchange for lease obligations	$ 38,754	$ 2,537