Commitments and Contingencies (Schedules of Future Minimum Rental Payments) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Land and Other Operating Leases [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due	$ 290
Operating Leases, Future Minimum Payments Due, Current	15
Operating Leases, Future Minimum Payments, Due in Two Years	15
Operating Leases, Future Minimum Payments, Due in Three Years	15
Operating Leases, Future Minimum Payments, Due in Four Years	15
Operating Leases, Future Minimum Payments, Due in Five Years	15
Operating Leases, Future Minimum Payments, Due Thereafter	215
Greenleaf [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due	11
KIAC [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due	143
Operating Leases, Future Minimum Payments Due, Current	24
Operating Leases, Future Minimum Payments, Due in Two Years	23
Operating Leases, Future Minimum Payments, Due in Three Years	22
Operating Leases, Future Minimum Payments, Due in Four Years	22
Operating Leases, Future Minimum Payments, Due in Five Years	22
Operating Leases, Future Minimum Payments, Due Thereafter	30
Total Power Plant Leases [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due	154
Operating Leases, Future Minimum Payments Due, Current	31
Operating Leases, Future Minimum Payments, Due in Two Years	27
Operating Leases, Future Minimum Payments, Due in Three Years	22
Operating Leases, Future Minimum Payments, Due in Four Years	22
Operating Leases, Future Minimum Payments, Due in Five Years	22
Operating Leases, Future Minimum Payments, Due Thereafter	30
Operating Leases, Rent Expense, Net	47		51	53
Operting Lease Assets Total [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due	444
Operating Leases, Future Minimum Payments Due, Current	46
Operating Leases, Future Minimum Payments, Due in Two Years	42
Operating Leases, Future Minimum Payments, Due in Three Years	37
Operating Leases, Future Minimum Payments, Due in Four Years	37
Operating Leases, Future Minimum Payments, Due in Five Years	37
Operating Leases, Future Minimum Payments, Due Thereafter	245
Office Equipment [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due	80
Operating Leases, Future Minimum Payments Due, Current	11
Operating Leases, Future Minimum Payments, Due in Two Years	10
Operating Leases, Future Minimum Payments, Due in Three Years	10
Operating Leases, Future Minimum Payments, Due in Four Years	11
Operating Leases, Future Minimum Payments, Due in Five Years	10
Operating Leases, Future Minimum Payments, Due Thereafter	28
Operating Leases, Rent Expense, Net	12		12	13
Greenleaf [Member]
Operating Leased Assets [Line Items]
Guarantee Obligations Balance On First Anniversary	7	[1]
Guarantee Obligations Balance On Second Anniversary	4	[1]
Guarantee Obligations Balance On Third Anniversary	0	[1]
Guarantee Obligations Balance On Fourth Anniversary	0	[1]
Guarantee Obligations Balance On Fifth Anniversary	0	[1]
Guarantee Obligations Due After Five Years	0	[1]
Natural Gas [Member]
Operating Leased Assets [Line Items]
Operating Leases, Future Minimum Payments Due	2,187
Operating Leases, Future Minimum Payments Due, Current	385
Operating Leases, Future Minimum Payments, Due in Two Years	290
Operating Leases, Future Minimum Payments, Due in Three Years	238
Operating Leases, Future Minimum Payments, Due in Four Years	235
Operating Leases, Future Minimum Payments, Due in Five Years	224
Operating Leases, Future Minimum Payments, Due Thereafter	$ 815

[1] These are contingent off balance sheet obligations.