Employee Benefit Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Employee Benefit Plans (Textual) [Abstract]
Provision for contributions to the Supplemental Plan	$ 245,000	$ 238,000	$ 241,000
Vesting period for the profit sharing contribution	3 years
US Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Description of Contribution by the company	contribution of 4%, 4% and 5%, respectively, of participants’ defined compensation and in each year matched upto 6% of each employee’s compensation contributed to the 401k Plan. Participants are fully vested in the employer match immediately upon enrollment in the 401k Plan and subject to a three year cliff vesting period for the profit sharing contribution.
Defined contribution plan, cost recognized	21,500,000	23,800,000	26,000,000
UK Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Description of Contribution by the company	contributions in an amount equal to the employee's contributions, generally up to a maximum of 5.25% of the employee's defined compensation per year for employees working in the U.K. sector of the North Sea and up to a maximum of 9% of the employee’s defined compensation per year for U.K. nationals working in the Norwegian sector of the North Sea.
Defined contribution plan, cost recognized	1,200,000	1,200,000	1,400,000
International Savings Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Description of Contribution by the company	contributed 4%, 4% and 5%, respectively, of participants’ defined compensation and in each year matched up to 6% of each employee’s compensation contributed to the International Savings Plan.
Defined contribution plan, cost recognized	$ 2,900,000	$ 2,800,000	$ 2,500,000