Property, Plant and Equipment (Schedule of Recognized Impairments) (Details) - USD ($)		3 Months Ended	12 Months Ended
		Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property Plant And Equipment [Line Items]
Impairment Expense			$ 95,088,000	$ 2,493,156,000	$ 51,314,000
Gulf Of Mexico [Member]
Property Plant And Equipment [Line Items]
Impairment Expense				328,982,000	14,267,000
Canada [Member]
Property Plant And Equipment [Line Items]
Impairment Expense		$ 37,047,000	95,088,000	683,574,000	37,047,000	[1]
Malaysia [Member]
Property Plant And Equipment [Line Items]
Impairment Expense	[2]			1,480,600,000
Conventional [Member] | Canada [Member]
Property Plant And Equipment [Line Items]
Impairment Expense	[2]		$ 95,100,000	$ 683,600,000	$ 37,000,000

[1] This amount represented the writeoff of goodwill associated with an oil and gas company acquired in 2000.

[2] Results exclude corporate overhead, interest and discontinued operations.