Employee Benefit Plans Employee Benefit Plans - Unrecognized Amounts (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Amortization of net loss	$ 47
Amoritization of prior service credit	(15)
Amortization of regulatory deferrals	(1)
Amounts that will be amortized in next fiscal year	31
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Net loss	361	660
Prior service credit	(29)	(37)
Regulatory deferrals	(4)	(5)
Total net periodic benefit cost not yet recognized	328	618	578
Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Net (gain) loss arising during the year	(242)	74
Net amortization	(48)	(34)
Total Net Periodic Benefit Cost Not Yet Recognized, Arising During Period	(290)	40
Amortization of net loss	38
Amoritization of prior service credit	(8)
Amortization of regulatory deferrals	(1)
Amounts that will be amortized in next fiscal year	29
Other Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Net loss	108	214
Prior service credit	(33)	(40)
Regulatory deferrals	2	3
Total net periodic benefit cost not yet recognized	77	177
Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Amortization of net loss	9
Amoritization of prior service credit	(7)
Amortization of regulatory deferrals	0
Amounts that will be amortized in next fiscal year	2
Regulatory Asset [Member] | Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net periodic benefit cost not yet recognized	313	599	564
Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Net (gain) loss arising during the year	(239)	68
Net amortization	(47)	(33)
Total Net Periodic Benefit Cost Not Yet Recognized, Arising During Period	(286)	35
Regulatory Asset [Member] | Other Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net periodic benefit cost not yet recognized	77	177	163
Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Net (gain) loss arising during the year	(92)	18
Net amortization	(8)	(4)
Total Net Periodic Benefit Cost Not Yet Recognized, Arising During Period	(100)	14
Accumulated Other Comprehensive Loss [Member] | Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Total net periodic benefit cost not yet recognized	15	19	14
Reconciliation of Amounts Not Yet Recognized As Components of Net Periodic Benefit Cost [Roll Forward]
Net (gain) loss arising during the year	(3)	6
Net amortization	(1)	(1)
Total Net Periodic Benefit Cost Not Yet Recognized, Arising During Period	$ (4)	$ 5