CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016
OPERATING ACTIVITIES
Net income (loss)		$ 40,893	$ (195,872)
Adjustments to reconcile net loss to net cash provided by continuing operations activities:
Income from discontinued operations		(752)	(708)
Depreciation, depletion and amortization		471,146	541,388
Impairment of assets			95,088
Amortization of deferred major repair costs			3,798
Dry hole costs		1,904	14,270
Amortization of undeveloped leases		20,306	25,419
Accretion of asset retirement obligations		20,984	24,471
Deferred income tax expense (benefit)		33,130	(316,201)
Pretax gains from disposition of assets		(130,648)	(3,831)
Net (increase) decrease in noncash operating working capital		42,581	(86,793)
Other operating activities, net		91,918	12,349
Net cash provided by continuing operations activities		591,462	113,378
Investing Activities
Property additions and dry hole costs		(431,654)	(604,587)
Proceeds from sales of property, plant and equipment		64,303	1,153,325
Purchases of investment securities	[1]	(212,661)	(651,218)
Proceeds from maturity of investment securities	[1]	284,193	701,378
Other investing activities, net			(7,640)
Net cash (required) provided by investing activities		(295,819)	591,258
Financing Activities
Repayments of debt			(600,000)
Capital lease obligation payments		(11,983)	(5,172)
Withholding tax on stock-based incentive awards		(7,081)	(1,138)
Cash dividends paid		(86,278)	(120,535)
Net cash required by financing activities		(105,342)	(726,845)
Cash Flows from Discontinued Operations
Operating activities			5,185
Changes in cash included in current assets held for sale			(5,185)
Net change in cash and cash equivalents of discontinued operations
Effect of exchange rate changes on cash and cash equivalents		(4,611)	6,509
Net increase in cash and cash equivalents		185,690	(15,700)
Cash and cash equivalents at beginning of period		872,797	283,183
Cash and cash equivalents at end of period		$ 1,058,487	$ 267,483

[1] Investments are Canadian government securities with maturities greater than 90 days at the date of acquisition.