Commitments and Contingencies (Schedules of Future Minimum Rental Payments) (Details) $ in Millions	Dec. 31, 2018 USD ($)
Land and Other Operating Leases [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	$ 13
Operating Leases, Future Minimum Payments, Due in Two Years	13
Operating Leases, Future Minimum Payments, Due in Three Years	12
Operating Leases, Future Minimum Payments, Due in Four Years	10
Operating Leases, Future Minimum Payments, Due in Five Years	10
Operating Leases, Future Minimum Payments, Due Thereafter	174
Operating Leases, Future Minimum Payments Due	232
KIAC [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	31
Operating Leases, Future Minimum Payments, Due in Two Years	0
Operating Leases, Future Minimum Payments, Due in Three Years	0
Operating Leases, Future Minimum Payments, Due in Four Years	0
Operating Leases, Future Minimum Payments, Due in Five Years	0
Operating Leases, Future Minimum Payments, Due Thereafter	0
Operating Leases, Future Minimum Payments Due	31
Operting Lease Assets Total [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	44
Operating Leases, Future Minimum Payments, Due in Two Years	13
Operating Leases, Future Minimum Payments, Due in Three Years	12
Operating Leases, Future Minimum Payments, Due in Four Years	10
Operating Leases, Future Minimum Payments, Due in Five Years	10
Operating Leases, Future Minimum Payments, Due Thereafter	174
Operating Leases, Future Minimum Payments Due	263
Natural Gas [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due, Next Twelve Months	415
Operating Leases, Future Minimum Payments, Due in Two Years	172
Operating Leases, Future Minimum Payments, Due in Three Years	134
Operating Leases, Future Minimum Payments, Due in Four Years	101
Operating Leases, Future Minimum Payments, Due in Five Years	93
Operating Leases, Future Minimum Payments, Due Thereafter	201
Operating Leases, Future Minimum Payments Due	$ 1,116