CONDENSED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net earnings	$ 57,552	$ 51,879
Adjustments to reconcile net earnings to net cash provided by operations:
Depreciation and amortization	40,996	36,474
Provision for deferred income taxes	21,497	18,183
Amortization of unearned share-based compensation	2,134	1,906
Other	2,155	1,211
Decrease in cash flows resulting from changes in operating assets and liabilities, net	(26,538)	(36,285)
Net cash provided by operating activities	97,796	73,368
Cash flows from investing activities:
Capital expenditures	(71,157)	(61,867)
Acquisition of businesses and marine equipment	(2,111)	0
Proceeds from disposition of assets	1,861	3,434
Net cash used in investing activities	(71,407)	(58,433)
Cash flows from financing activities:
Payments on bank credit facilities, net	(43,650)	(22,510)
Borrowings on long-term debt	225,000	0
Payments on long-term debt	(213,000)	(6,502)
Proceeds from exercise of stock options	2,262	1,001
Payment of contingent liability	(5,000)	0
Excess tax benefit from equity compensation plans	1,866	2,337
Other	(1,088)	(465)
Net cash used in financing activities	(33,610)	(26,139)
Decrease in cash and cash equivalents	(7,221)	(11,204)
Cash and cash equivalents, beginning of year	11,059	16,249
Cash and cash equivalents, end of period	3,838	5,045
Cash paid (received) during the period:
Interest	5,420	5,342
Income taxes	$ (177)	$ 749