Investment Securities (Gains (Losses) on Sales of Securities Available for Sale) (Details) - USD ($)	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Investment Securities Disclosure [Abstract]
Proceeds	$ 2,441,000,000	$ 3,401,000,000
Gross Gains	51,000,000	29,000,000
Gross Losses	(1,000,000)	(25,000,000)
Net Gains	50,000,000	4,000,000
Tax Expense	$ 17,000,000	$ 1,000,000