CONDENSED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net earnings	$ 103,409	$ 82,406
Adjustments to reconcile net earnings to net cash provided by operations:
Depreciation and amortization	167,640	147,669
Provision for deferred income taxes	36,838	32,783
Amortization of unearned share-based compensation	16,649	8,991
Amortization of major maintenance costs	15,600	15,232
Amortization of debt issuance costs	898	786
Other	(2,023)	180
Decrease in cash flows resulting from changes in operating assets and liabilities, net	(66,707)	(28,592)
Net cash provided by operating activities	272,304	259,455
Cash flows from investing activities:
Capital expenditures	(231,752)	(133,437)
Acquisitions of businesses and marine equipment, net of cash acquired	(499,227)	(451,219)
Proceeds from disposition of assets	27,806	29,743
Net cash used in investing activities	(703,173)	(554,913)
Cash flows from financing activities:
Borrowings (payments) on bank credit facilities	(88,392)	298,424
Borrowings (payments) on long-term debt	499,295	(1,065)
Payments of debt issue costs	(4,276)	(1,243)
Proceeds from exercise of stock options	13,264	2,076
Payments related to tax withholding for share-based compensation	(4,821)	(2,899)
Other	(686)	(643)
Net cash provided by financing activities	414,384	294,650
Decrease in cash and cash equivalents	(16,485)	(808)
Cash and cash equivalents, beginning of year	20,102	5,634
Cash and cash equivalents, end of period	3,617	4,826
Cash paid during the period:
Interest paid	37,175	18,390
Income taxes	495	19,388
Capital expenditures included in accounts payable	(5,554)	8,917
Non-cash investing activity:
Stock issued in acquisition	0	366,554
Cash acquired in acquisition	2,313	98
Debt assumed in acquisition	$ 0	$ 13,724