Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income (loss)	$ (1,854,718)	$ 257,817	$ (111,418)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, amortization and accretion	612,147	652,143	625,928
Deferred income taxes	(288,671)	(49,567)	14,435
Reduction in value of assets including discontinued operations	1,738,887		419,380
Stock based and performance share unit compensation expense	46,485	42,748	35,832
Amortization of debt acquisition costs and note discount	7,643	8,110	8,919
(Gains) losses on sales of assets and businesses	(14,803)	(12,777)	(657)
Other reconciling items, net	49,042	(6,803)	(899)
Changes in operating assets and liabilities, net of acquisitions and dispositions:
Accounts receivable	501,269	(9,487)	85,423
Inventory and other current assets	33,282	53,594	(70,995)
Accounts payable	(105,801)	36,450	(32,304)
Accrued expenses	(116,573)	16,411	25,154
Income taxes	(30,891)	46,134	(162,148)
Other, net	55,314	(1,762)	56,158
Net Cash Provided by (Used in) Operating Activities, Total	632,612	1,033,011	892,808
Cash flows from investing activities:
Payments for capital expenditures	(358,226)	(616,102)	(608,960)
Purchase of leased vessels	46,442
Proceeds from Sale of Available-for-sale Securities, Equity		10,622
Acquisitions of businesses, net of cash acquired		(24,327)	(23,797)
Cash Proceeds From Sales of Assets And Businesses	14,110	147,305	6,292
Proceeds from Insurance Settlement, Investing Activities			22,650
Other	2,290	7,767	(1,753)
Net Cash Provided by (Used in) Investing Activities, Total	(388,268)	(474,735)	(605,568)
Cash flows from financing activities:
Repayments of Long-term Lines of Credit	(7,475)	(14,736)	(581,771)
Proceeds from Long-term Lines of Credit	7,475	14,736	581,771
Payment to extinguish capital lease obligation	20,933
Proceeds from issuance of long-term debt	14,733	2,602
Principal payments of long-term debt	(21,038)	(21,564)	(170,000)
Share repurchases		(299,734)	(10,627)
Cash dividends	(48,139)	(49,756)
Proceeds from exercise of stock options	8,820	10,560	6,264
Proceeds from issuance of stock through employee benefit plans	4,803	4,870	4,124
Other	(2,302)	724	(6,840)
Net Cash Provided by (Used in) Financing Activities, Total	(68,859)	(357,168)	(181,203)
Effect of exchange rate changes on cash	(4,514)	(4,109)	(1,189)
Net increase in cash and cash equivalents	170,971	196,999	104,848
Cash and cash equivalents at beginning of period	393,046	196,047	91,199
Cash and cash equivalents at end of period	$ 564,017	$ 393,046	$ 196,047