Supplemental Information On Oil And Gas Producing Activities (Standardized Measure Of Discounted Future Net Cash Flows Relating To Proved Oil Reserves) (Detail) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil Reserves
Future cash inflows		$ 143,276	$ 823,657	$ 733,761
Future production costs		(83,617)	(308,806)	(226,681)
Future development costs	[1]	(11,159)	(136,137)	(164,142)
Future income tax expense		(21,598)	(178,283)	(155,344)
Future net cash flows		26,902	200,431	187,594
Discount to present value at 10% annual rate		239	(51,044)	(50,158)
Standardized measure of discounted future net cash flows		27,141	149,387	137,436	$ 152,902
International [Member]
Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil Reserves
Future cash inflows		140,190	814,059	725,485
Future production costs		(81,973)	(307,331)	(223,643)
Future development costs	[1]	(10,900)	(136,137)	(164,142)
Future income tax expense		(21,598)	(177,924)	(154,519)
Future net cash flows		25,719	192,667	183,181
Discount to present value at 10% annual rate		491	(47,528)	(48,859)
Standardized measure of discounted future net cash flows		26,210	145,139	134,322
United States [Member]
Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil Reserves
Future cash inflows		3,086	9,598	8,276
Future production costs		(1,644)	(1,475)	(3,038)
Future development costs	[1]	(259)
Future income tax expense			(359)	(825)
Future net cash flows		1,183	7,764	4,413
Discount to present value at 10% annual rate		(252)	(3,516)	(1,299)
Standardized measure of discounted future net cash flows		$ 931	$ 4,248	$ 3,114

[1] Includes costs expected to be incurred to abandon the properties.