Employee Benefit Plans - Schedule of Assumptions Used (Details)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.14%	[1],[2]	5.01%	[1],[2]
Defined benefit plan, assumptions used calculating net periodic benefit cost, expected long-term return on assets	9.00%
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	4.99%	[1]	4.10%	[1]	4.95%	[1]
Other Postretirement and Postemployment Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	4.88%	[1],[3]	4.00%	[1],[3]	4.63%	[1],[3]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year	7.00%	[1],[4]	7.00%	[1],[4]	7.00%	[1],[4]
Other Pension Plans, Postretirement or Supplemental Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	5.00%	[1]	4.13%	[1]	4.88%	[1]
Defined benefit plan, assumptions used calculating net periodic benefit cost, expected long-term return on assets	8.94%	[1]	8.94%	[1]	8.94%	[1]

[1] Future compensation levels do not impact our frozen defined benefit pension plans or other postretirement plans and impact only a small portion of our other postemployment liability.

[2] Our 2014 and 2013 benefit obligations are measured using a mortality table projected to 2022 and 2017, respectively.

[3] Our assumptions reflect various remeasurements of certain portions of our obligations and represent the weighted average of the assumptions used for each measurement date.

[4] Assumed healthcare cost trend rate at December 31, 2014 is assumed to decline gradually to 5.00% by 2024 and remain level thereafter.