Employee Retirement Plans and Postretirement Benefits Weighted Average Assumptions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 29, 2012
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]
Effect on total of service and interest cost components, one-percent point increase (unfavorable)	(1.3)
Effect on total of service and interest cost components, one-percent point decrease favorable	1.5
Effect on postretirement benefit obligation, one-percent point increase (unfavorable)	(23.0)
Effect on postretirement benefit obligation, one-percent point decrease favorable	19.6
Pension
Defined Benefit Plan Disclosure [Line Items]
Settlement discount rate	4.57%		4.18%		4.61%
Rate of compensation increase (as a percent)	2.50%	[1]	2.50%	[1]	2.50%	[1]
Expected return on plan assets (as a percent)	6.16%	[2]	5.83%	[2]	5.57%	[2]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.70%		4.57%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	2.50%	[1]	2.50%	[1]
OPEB
Defined Benefit Plan Disclosure [Line Items]
Settlement discount rate	4.79%		4.12%		4.66%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.15%		4.79%
OPEB | Maximum
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate	7.70%		7.90%
Year that rate reaches ultimate trend rate	2014
OPEB | Minimum
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate	4.50%		4.50%
Year that rate reaches ultimate trend rate	2028

[1] U.K. plan was closed to future accrual during 2009.

[2] We develop our long term expected return on assets ("EROA") assumptions annually with input from independent investment specialists including our actuaries, investment consultants and other specialists. Each EROA assumption is based on historical data, including historical returns, historical market rates and is calculated for each plan's individual asset class. The calculation includes inputs for interest, inflation, credit, and risk premium (active investment management) rates and fees paid to service providers. We consider our EROA to be a significant management estimate. Any material changes in the inputs to our methodology used in calculating our EROA could have a significant impact on our reported defined benefit pension plans' expense.