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Commitments and Contingencies (Details Textual)	12 Months Ended														12 Months Ended					12 Months Ended
Commitments and Contingencies (Details Textual)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)	Dec. 31, 2011 AUD	May 28, 2009 AUD	Dec. 31, 2011 Alcoa [Member] USD ($)	Dec. 31, 2011 Oswal [Member] USD ($)	Jan. 31, 2012 Burrup Holdings Limited [Member]	Jan. 31, 2012 Yara International [Member]	Aug. 31, 2011 Phoenix [Member]	Dec. 31, 2011 Pension Benefits [Member] USD ($)	Dec. 31, 2010 Pension Benefits [Member] USD ($)	Dec. 31, 2009 Pension Benefits [Member] USD ($)	Dec. 31, 2011 Postretirement Benefits [Member] USD ($)	Dec. 31, 2010 MSCI world index [Member]	Dec. 31, 2011 FTSE Actuaries Government Securities Index [Member]	Dec. 31, 2011 iBoxx Sterling Overall Index [Member]	Dec. 31, 2011 UK Quoted Equities [Member]	Dec. 31, 2010 UK Quoted Equities [Member]	Dec. 31, 2011 Overseas Quoted Equities [Member]	Dec. 31, 2010 Overseas Quoted Equities [Member]	Dec. 31, 2011 U.K. Government bonds [Member]	Dec. 31, 2010 U.K. Government bonds [Member]	Dec. 31, 2011 U.K. Government bonds [Member] Index - Linked Index [Member]	Dec. 31, 2010 U.K. Government bonds [Member] Index - Linked Index [Member]	Dec. 31, 2011 U.K. corporate bonds [Member]	Dec. 31, 2011 U.K. corporate bonds [Member] Index - Linked Index [Member]	Dec. 31, 2011 Global Equities [Member]	Dec. 31, 2010 Global Equities [Member]	Dec. 31, 2011 Emerging markets [Member]	Dec. 31, 2010 Emerging markets [Member]
Loss Contingencies [Line Items]
Accumulated benefit obligation for pension plans											$ 119,000,000	$ 107,000,000	$ 89,000,000
Performance target over the benchmark																				2.00%	2.00%
Performance target per annum over benchmark against iBoxx Sterling Overall Index																						0.75%	0.75%
Period for the portion of UK Equities, overseas equities, government bonds and corporate bonds, benchmarked against FTSE															3 years	5 years	3 years
Portion of debt securities government bonds and corporate bonds benchmarked against FTSE																								65.00%	28.00%	53.00%	47.00%
Expected contribution towards pension and postretirement plans											5,000,000			1,000,000
Portion of overseas equities, benchmarked against MSCI World Index	48.00%	52.00%																17.00%	18.00%	31.00%	34.00%							85.00%	85.00%	15.00%	15.00%
Portion of debt securities government bonds and corporate bonds benchmarked against iBoxx Sterling Overall Index																						35.00%	72.00%
Percentage of acquisition								49.00%	51.00%
Percentage of general partner interest acquired										75.00%
Percentage of limited partner interest acquired										75.00%
Maximum Expected contractual general damages under long term contracts						158,000,000	491,000,000
Commitments and Contingencies (Textual) [Abstract]
Net rental expenses	64,000,000	46,000,000	38,000,000
Approximate percentage of natural gas volumes sold under long-term contracts that have liquidated damages provisions	90.00%
Accrued liability for legal contingencies	20,000,000
Outperformance relative to gilts for equities	3.50%	3.50%
Targeted ongoing funding level of pension plan policy, percent	100.00%
Annual cost of retirement benefit plans	93,000,000	80,000,000	66,000,000
Portion occurring as money purchase retirement plan and the non-qualified retirement/savings plan, vested	20.00%
Maximum percentage of compensation contributed by the company	8.00%
Portion of employee's salary, employee contributions under non-qualified retirement savings plan	50.00%
Maximum percentage of eligible compensation contributed by the participating employees	50.00%
Undiscounted reserve for environmental remediation	120,000,000
Percentage of combined ownership held by the plaintiff in the company	65.00%
Validity of pipeline license	21 years
Maximum expected contractual liquidated damages under long term contracts	5,700,000			200,000,000
Maximum cost considered to be recognized for additional reserve	300,000
Maximum fine associated with the alleged offense					50,000
Damages sought by plaintiffs	100,000,000
Cost for the restoration of plaintiffs' property	$ 61,000,000
Percentage of additional contribution to money purchase retirement plan	6.00%
Portion of employee's annual bonus, employee contributions under non-qualified retirement savings plan, vested	75.00%