Lease Obligations (Details 1) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Mainline [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Current	$ 1,079	[1]
Operating Leases, Future Minimum Payments, Due in Two Years	1,028	[1]
Operating Leases, Future Minimum Payments, Due in Three Years	900	[1]
Operating Leases, Future Minimum Payments, Due in Four Years	785	[1]
Operating Leases, Future Minimum Payments, Due in Five Years	635	[1]
Operating Leases, Future Minimum Payments, Due Thereafter	5,442	[1]
Operating Leases, Future Minimum Payments Due	9,869	[1]
Regional Carrier [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Current	350
Operating Leases, Future Minimum Payments, Due in Two Years	328
Operating Leases, Future Minimum Payments, Due in Three Years	286
Operating Leases, Future Minimum Payments, Due in Four Years	241
Operating Leases, Future Minimum Payments, Due in Five Years	196
Operating Leases, Future Minimum Payments, Due Thereafter	224
Operating Leases, Future Minimum Payments Due	1,625
Reporting Entity [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Current	1,429
Operating Leases, Future Minimum Payments, Due in Two Years	1,356
Operating Leases, Future Minimum Payments, Due in Three Years	1,186
Operating Leases, Future Minimum Payments, Due in Four Years	1,026
Operating Leases, Future Minimum Payments, Due in Five Years	831
Operating Leases, Future Minimum Payments, Due Thereafter	5,666
Operating Leases, Future Minimum Payments Due	$ 11,494

[1] (1) Includes payments accounted for as construction obligations. See Note 5.