Pension and Other Post-Retirement Benefit Plans (Schedule of Assumptions) (Details)	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plans [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Expected return on plan assets	6.25%	6.25%	6.25%
Crewmembers [Member] | Pension Plans [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	4.50%	4.70%	4.35%
Non-crewmembers [Member] | Pension Plans [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	4.60%	4.75%	4.40%
Pilots [Member] | Post-Retirement Healthcare Plans [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	3.55%	3.65%	3.35%
Non-pilots [Member] | Post-Retirement Healthcare Plans [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate		3.35%	3.30%