Employee Benefits (Details 2)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Net periodic cost
Weighted-average healthcare cost rate	5.00%
Retirement Plans [Member]
Benefit obligation
Discount rate	4.10%	[1]	5.10%	[1]	5.40%	[1]
Compensation increase factor			4.50%	[1]	4.50%	[1]
Net periodic cost
Discount rate	5.10%	[2]	5.40%	[2]	5.95%	[2]
Compensation increase factor	4.50%		4.50%		5.50%
Return on assets	7.75%	[3]	8.00%	[3]	8.00%	[3]
Postretirement Plans [Member]
Benefit obligation
Discount rate	3.45%	[1]	4.45%	[1]	4.65%	[1]
Net periodic cost
Weighted-average healthcare cost rate	7.50%	[4]	8.00%	[4]	8.00%	[4]
Discount rate	4.45%	[2]	4.65%	[2]	5.30%	[2]
United Kingdom Retirement Plan [Member]
Net periodic cost
Discount rate	5.10%	[2]	5.50%	[2]	5.90%	[2]
Compensation increase factor	5.85%		6.25%		6.25%

[1] These assumptions for the retirement plans relate to our U.S. ERP and a compensation increase factor is no longer applicable for 2012 because there are no further salary increases as the U.S. ERP was frozen in April 2012.

[2] Effective January 1, 2013, we changed our discount rate assumption on our U.S. retirement plans to 4.1% from 5.1% in 2012 and changed our discount rate assumption on our U.K. plan to 4.8% from 5.1% in 2012.

[3] The expected return on assets assumption is calculated based on the plan’s asset allocation strategy and projected market returns over the long-term. Effective January 1, 2013, we changed our return on assets assumption to 7.25% from 7.75% in 2012.

[4] The assumed weighted-average healthcare cost trend rate will decrease ratably from 7.5% in 2012 to 5% in 2018 and remain at that level thereafter. Assumed healthcare cost trends have an effect on the amounts reported for the healthcare plans. A one percentage point change in assumed healthcare cost trend creates the following effects:(in millions)1% pointincrease 1% pointdecreaseEffect on postretirement obligation$4 $(4)