CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net earnings	$ 143,019	$ 79,078	$ 313,903
Adjustments to reconcile net earnings to net cash provided by operations:
Depreciation and amortization	219,632	224,972	202,881
Provision (credit) for doubtful accounts	(873)	1,289	224
Provision (benefit) for deferred income taxes	46,839	34,881	(256,263)
Loss (gain) on disposition of assets	(8,152)	(1,968)	4,487
Equity in earnings of affiliates, net of distributions and contributions	471	(355)	732
Impairment and other charges	35,525	85,407	105,712
Amortization of unearned share-based compensation	13,612	19,104	11,460
Amortization of leases	(490)	0	0
Amortization of major maintenance costs	23,962	20,760	21,207
Amortization of debt issuance costs	1,702	1,218	986
Increase (decrease) in cash flows resulting from changes in:
Accounts receivable	43,078	12,511	(60,405)
Inventory	122,773	(144,685)	19,673
Other assets	(25,470)	(38,090)	(17,049)
Income taxes payable	(2,503)	(457)	(11,823)
Accounts payable	(57,405)	22,622	20,758
Accrued and other liabilities	(43,907)	30,712	(3,105)
Net cash provided by operating activities	511,813	346,999	353,378
Cash flows from investing activities:
Capital expenditures	(248,164)	(301,861)	(177,222)
Acquisitions of businesses and marine equipment, net of cash acquired	(262,491)	(533,897)	(470,101)
Proceeds from disposition of assets	57,657	53,392	54,229
Other	0	(250)	0
Net cash used in investing activities	(452,998)	(782,616)	(593,094)
Cash flows from financing activities:
Borrowings (payments) on bank credit facilities, net	(417,376)	(78,455)	269,859
Borrowings on long-term debt	500,000	499,295	0
Payments on long-term debt	(125,000)	0	(13,721)
Payment of debt issue costs	(2,397)	(4,276)	(1,243)
Return of investment to noncontrolling interests	(817)	(915)	(862)
Proceeds from exercise of stock options	5,743	13,264	3,039
Purchase of treasury stock	0	(776)	0
Payments related to tax withholding for share-based compensation	(2,031)	(4,822)	(2,881)
Acquisitions of noncontrolling interest	0	0	(7)
Net cash provided by (used in) financing activities	(41,878)	423,315	254,184
Increase (decrease) in cash and cash equivalents	16,937	(12,302)	14,468
Cash and cash equivalents, beginning of year	7,800	20,102	5,634
Cash and cash equivalents, end of year	24,737	7,800	20,102
Cash paid during the period:
Interest paid	55,766	40,772	21,663
Income taxes paid	2,926	640	27,196
Operating cash outflow from operating leases	39,376	0	0
Non-cash investing activity:
Capital expenditures included in accounts payable	13,875	(16,441)	5,525
Stock issued in acquisition	0	0	366,554
Cash acquired in acquisition	0	2,313	98
Debt assumed in acquisition	0	0	13,724
Right-of-use assets obtained in exchange for lease obligations	$ 21,195	$ 0	$ 0