CONDENSED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net earnings	$ 82,406	$ 109,946
Adjustments to reconcile net earnings to net cash provided by operations:
Depreciation and amortization	147,669	148,427
Provision for deferred income taxes	32,783	46,264
Amortization of unearned share-based compensation	8,991	8,841
Amortization of major maintenance costs	15,232	14,210
Amortization of debt issuance costs	786	600
Other	180	(1,090)
Increase (decrease) in cash flows resulting from changes in operating assets and liabilities, net	(28,592)	11,048
Net cash provided by operating activities	259,455	338,246
Cash flows from investing activities:
Capital expenditures	(133,437)	(169,305)
Acquisitions of businesses and marine equipment, net of cash acquired	(451,219)	(125,632)
Proceeds from disposition of assets	29,743	15,136
Net cash used in investing activities	(554,913)	(279,801)
Cash flows from financing activities:
Borrowings (payments) on bank credit facilities, net	297,181	(49,445)
Payments on long-term debt	(1,065)	0
Proceeds from exercise of stock options	2,076	321
Purchase of treasury stock	0	(1,827)
Acquisition of noncontrolling interests	(7)	(4,160)
Payments related to tax withholding for share-based compensation	(2,899)	(1,753)
Other	(636)	(2,085)
Net cash provided by (used in) financing activities	294,650	(58,949)
Decrease in cash and cash equivalents	(808)	(504)
Cash and cash equivalents, beginning of year	5,634	5,885
Cash and cash equivalents, end of period	4,826	5,381
Cash paid during the period:
Interest paid	18,390	18,930
Income taxes paid	19,388	14,901
Capital expenditures included in accounts payable	8,917	(2,296)
Non-cash investing activity:
Fair value of property transferred in acquisition	0	3,681
Stock issued in acquisition	366,554	0
Cash acquired in acquisition	98	0
Debt assumed in acquisition	$ 13,724	$ 0