Condensed Financial Information (Parent Company) (Interest Expense) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Interest Expense [Abstract]
Total interest expense	$ 854	$ 871	$ 975
Parent Company [Member]
Interest Expense [Abstract]
Total interest expense	1,122	985	1,007
Parent Company [Member] | Long-term Debt [Member]
Interest Expense [Abstract]
Total interest expense	790	779	806
Parent Company [Member] | Long-term Debt [Member] | Affiliated Entity [Member]
Interest Expense [Abstract]
Total interest expense	163	28	16
Parent Company [Member] | Secured Debt [Member]
Interest Expense [Abstract]
Total interest expense	35	42	43
Parent Company [Member] | Junior Subordinated Debt [Member]
Interest Expense [Abstract]
Total interest expense	134	134	134
Parent Company [Member] | Stock Purchase Contracts [Member]
Interest Expense [Abstract]
Total interest expense	$ 0	$ 2	$ 8