Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net income	$ (86,803)	$ (11,135)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion, amortization and accretion	136,672	162,223
Deferred income taxes	(55,371)	(4,767)
Stock based and performance share unit compensation expense	10,783	11,816
Other reconciling items, net	(63)	4,681
Changes in operating assets and liabilities, net of acquisitions and dispositions:
Accounts receivable	71,602	168,412
Inventory and other current assets	(6,529)	(14,992)
Accounts payable	(14,979)	(20,800)
Accrued expenses	(5,307)	(38,152)
Income taxes	8,987	(30,973)
Other, net	3,543	11,955
Net Cash Provided by (Used in) Operating Activities, Total	62,535	238,268
Cash flows from investing activities:
Payments for capital expenditures	(38,015)	(127,487)
Purchase of Leased Vessel		46,442
Other	1,880	1,900
Net Cash Provided by (Used in) Investing Activities, Total	(36,135)	(172,029)
Cash flows from financing activities:
Payment to Extinguish Capital Lease Obligation		20,933
Principal payments of long-term debt	(329,106)	(5,233)
Payment of debt acquisition costs	(2,364)
Payments of Ordinary Dividends, Common Stock	12,111	11,984
Proceeds from exercise of stock options		6,208
Other	(8,366)	(6,367)
Net Cash Provided by (Used in) Financing Activities, Total	(26,947)	(38,309)
Proceeds From Revolving Line Of Credit	325,000
Effect of exchange rate changes on cash	(4,232)	(6,147)
Net increase in cash and cash equivalents	(4,779)	21,783
Cash and cash equivalents at beginning of period	564,017
Cash and cash equivalents at end of period	$ 559,238	$ 414,829