Other Financial Information (Narrative) (Details)	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) item	Dec. 31, 2014 USD ($)
Other Financial Information [Line Items]
Deepwater rig contract exit costs	$ (4,344,000)	$ 282,001,000
Payment of contract exit costs	266,700,000
Write down of accrued contract exit costs	4,330,000
Net gains (losses) from foreign currency transactions	$ 59,731,000	$ 87,961,000	$ 40,596,000
Gulf Of Mexico [Member]
Other Financial Information [Line Items]
Number of deepwater drilling rigs | item		2