CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
OPERATING ACTIVITIES
Net income (loss)		$ 58,464	$ (198,802)
Adjustments to reconcile net income (loss) to net cash provided by continuing operations activities:
Income from discontinued operations		(969)	(683)
Depreciation, depletion and amortization		236,154	286,149
Impairment of assets			95,088
Amortization of deferred major repair costs			2,002
Dry hole costs		2,904	(69)
Amortization of undeveloped leases		9,957	10,469
Accretion of asset retirement obligations		10,556	12,125
Deferred income tax expense (benefit)		58,533	(85,683)
Pretax gains from disposition of assets		(131,982)	(22)
Net (increase) decrease in noncash operating working capital	[1]	43,418	(104,347)
Other operating activities, net		18,478	27,085
Net cash provided by continuing operations activities		305,513	43,312
INVESTING ACTIVITIES
Property additions and dry hole costs		(211,631)	(210,029)
Proceeds from sales of property, plant and equipment		64,097	33
Purchase of investment securities	[2]	(212,661)	(49,277)
Proceeds from maturity of investment securities	[2]	113,210	86,983
Other investing activities, net			(21,658)
Net cash required by investing activities		(246,985)	(193,948)
FINANCING ACTIVITIES
Borrowings of debt			371,000
Capital lease obligation payments		(9,660)	(2,690)
Withholding tax on stock-based incentive awards		(5,808)	(1,052)
Cash dividends paid		(43,136)	(60,267)
Net cash provided (required) by financing activities		(58,604)	306,991
CASH FLOWS FROM DISCONTINUED OPERATIONS
Operating activities			2,312
Changes in cash included in current assets held for sale			(2,312)
Net increase in cash and cash equivalents of discontinued operations
Effect of exchange rate changes on cash and cash equivalents		3,132	(16,475)
Net increase in cash and cash equivalents		3,056	139,880
Cash and cash equivalents at January 1		872,797	283,183
Cash and cash equivalents at March 31		$ 875,853	$ 423,063

[1] 2016 balance includes payments for deepwater rig contract exit of $253.2 million.

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