CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net loss	$ (3,120)	$ (346,963)
Adjustments to reconcile net loss to net cash provided by operations:
Depreciation and amortization	54,890	55,786
Benefit for deferred income taxes	(533)	(35,242)
Impairments and other charges	0	561,274
Amortization of unearned share-based compensation	5,722	5,331
Amortization of major maintenance costs	8,360	7,103
Other	(1,138)	112
Increase (decrease) in cash flows resulting from changes in operating assets and liabilities, net	38,377	(175,900)
Net cash provided by operating activities	102,558	71,501
Cash flows from investing activities:
Capital expenditures	(14,052)	(49,225)
Acquisitions of businesses and marine equipment	0	(60,422)
Proceeds from disposition of assets	4,754	3,993
Net cash used in investing activities	(9,298)	(105,654)
Cash flows from financing activities:
Borrowings (payments) on bank credit facilities, net	(119,606)	485,001
Payments on long-term debt	0	(150,000)
Proceeds from exercise of stock options	411	353
Payments related to tax withholding for share-based compensation	(2,045)	(3,165)
Return of investment to noncontrolling interest	(25)	(202)
Net cash provided by (used in) financing activities	(121,265)	331,987
Increase (decrease) in cash and cash equivalents	(28,005)	297,834
Cash and cash equivalents, beginning of year	80,338	24,737
Cash and cash equivalents, end of period	52,333	322,571
Cash paid (received) during the period:
Interest paid	18,732	21,734
Income taxes refunded	(117,659)	(160)
Operating cash outflow from operating leases	10,688	9,738
Non-cash investing activity:
Capital expenditures included in accounts payable	(7,207)	(2,707)
Right-of-use assets obtained in exchange for lease obligations	$ 6,219	$ 4,677