Property, Plant And Equipment (Net Changes in Capitalized Exploratory Well Costs) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant And Equipment [Abstract]
Beginning balance at January 1	$ 130,514,000	$ 120,455,000	$ 393,030,000
Additions to capitalized exploratory well costs pending the determination of proved reserves	17,986,000	64,578,000	2,874,000
Reclassifications to proved properties based on the determination of proved reserves			(91,236,000)
Reduction of capitalized exploratory well costs due to partial asset sale in Malaysia			(122,175,000)
Capitalized exploratory well costs charged to expense		(54,519,000)	(62,038,000)
Balance at December 31	$ 148,500,000	$ 130,514,000	$ 120,455,000