Employee Retirement Benefits (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended														12 Months Ended	3 Months Ended	12 Months Ended							12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2008	Dec. 31, 2013 Domestic Equity Securities [Member]	Dec. 31, 2013 Domestic Equity Securities [Member] Information Technology Sector [Member]	Dec. 31, 2013 Domestic Equity Securities [Member] Financial Services Sector [Member]	Dec. 31, 2013 Domestic Equity Securities [Member] Healthcare Sector [Member]	Dec. 31, 2013 Domestic Equity Securities [Member] Industrial Sector [Member]	Dec. 31, 2013 Domestic Equity Securities [Member] All Remaining Sectors [Member]	Dec. 31, 2013 States, Municipalities And Political Subdivisions [Member]	Dec. 31, 2013 Domestic Corporate Debt Securities [Member]	Dec. 31, 2013 Cash and Cash Equivalents [Member]	Dec. 31, 2012 Cash and Cash Equivalents [Member]	Dec. 31, 2013 Maximum [Member]	Mar. 31, 2014 Qualified Pension Plan [Member]	Dec. 31, 2013 Qualified Pension Plan [Member]	Dec. 31, 2012 Qualified Pension Plan [Member]	Dec. 31, 2013 Qualified Pension Plan [Member] Benefit Obligations [Member]	Dec. 31, 2013 Qualified Pension Plan [Member] Net Periodic Benefit Costs [Member]	Dec. 31, 2014 Supplemental Executive Retirement Plan (SERP) [Member]	Dec. 31, 2013 Supplemental Executive Retirement Plan (SERP) [Member]	Dec. 31, 2012 Supplemental Executive Retirement Plan (SERP) [Member]	Dec. 31, 2013 Supplemental Executive Retirement Plan (SERP) [Member] Benefit Obligations [Member]	Dec. 31, 2013 Supplemental Executive Retirement Plan (SERP) [Member] Net Periodic Benefit Costs [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Minimum participant age to elect				40 years
Benefits paid	$ 28	$ 15
Matching contributions for 401(k) plan	10	9	8
Total recognized in net periodic benefit cost and other comprehensive income	63	(31)	(38)
Amortization of actuarial loss	2
Amortization of prior service cost	1
Matching contribution to defined contribution plan															6.00%
Defined Contribution Plan, Requisite Service Period	3 years
Accrued employee benefit																						9	9
Percentage of decrease in discount rate																			0.95%	0.90%				0.85%	0.80%
Allocation percentage of investments					80.00%	22.00%	22.00%	12.00%	12.00%	10.00%	12.00%	8.00%
Pension plan assets at fair value	280	238	216										19	3
Pension plan assets, shares																	467,113	567,113
Pension plan assets, fair value																	24	22
Pension plan assets, sold shares																	100,000
Pension plan assets, entity's shares sold, gain																	5
Cash dividends paid	270	263	261														1	1
Expected contribution by employer during 2013																$ 5					$ 2
Defined Benefit Plan, Actual Return on Plan Assets Still Held	24.00%