CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net earnings (loss)	$ (271,592)	$ 143,019	$ 79,078
Adjustments to reconcile net earnings (loss) to net cash provided by operations:
Depreciation and amortization	219,921	219,632	224,972
Provision (credit) for doubtful accounts	3,716	(873)	1,289
Provision for deferred income taxes	25,163	46,839	34,881
Gain on disposition of assets	(118)	(8,152)	(1,968)
Impairments and other charges	561,274	35,525	85,407
Amortization of unearned share-based compensation	14,722	13,612	19,104
Amortization of major maintenance costs	30,214	23,962	20,760
Other	(90)	1,683	863
Increase (decrease) in cash flows resulting from changes in:
Accounts receivable	(124,941)	43,078	12,511
Inventory	47,076	122,773	(144,685)
Other assets	(29,994)	(25,470)	(38,090)
Income taxes payable	8,826	(2,503)	(457)
Accounts payable	(39,795)	(57,405)	22,622
Accrued and other liabilities	558	(43,907)	30,712
Net cash provided by operating activities	444,940	511,813	346,999
Cash flows from investing activities:
Capital expenditures	(148,185)	(248,164)	(301,861)
Acquisitions of businesses and marine equipment, net of cash acquired	(354,972)	(262,491)	(533,897)
Proceeds from disposition of assets and other	17,310	57,657	53,142
Net cash used in investing activities	(485,847)	(452,998)	(782,616)
Cash flows from financing activities:
Borrowings (payments) on bank credit facilities, net	250,024	(417,376)	(78,455)
Borrowings on long-term debt	0	500,000	499,295
Payments on long-term debt	(150,000)	(125,000)	0
Payment of debt issue costs	0	(2,397)	(4,276)
Return of investment to noncontrolling interests	(676)	(817)	(915)
Proceeds from exercise of stock options	353	5,743	13,264
Purchase of treasury stock	0	0	(776)
Payments related to tax withholding for share-based compensation	(3,193)	(2,031)	(4,822)
Net cash provided by (used in) financing activities	96,508	(41,878)	423,315
Increase (decrease) in cash and cash equivalents	55,601	16,937	(12,302)
Cash and cash equivalents, beginning of year	24,737	7,800	20,102
Cash and cash equivalents, end of year	80,338	24,737	7,800
Cash paid (received) during the period:
Interest paid	48,721	55,766	40,772
Income taxes paid (refunded)	(35,571)	2,926	640
Operating cash outflow from operating leases	43,639	39,376	0
Non-cash investing activity:
Capital expenditures included in accounts payable	(13,280)	13,875	(16,441)
Cash acquired in acquisition	557	0	2,313
Right-of-use assets obtained in exchange for lease obligations	$ 46,511	$ 21,195	$ 0