Shareholders' Equity (Narrative) (Details) (USD $)	12 Months Ended											1 Months Ended	6 Months Ended	12 Months Ended	3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2013 Retained Earnings	Dec. 31, 2012 Retained Earnings	Dec. 31, 2011 Retained Earnings	Dec. 31, 2013 Series C Preferred Stock	Dec. 31, 2012 Series C Preferred Stock	Dec. 31, 2013 Depositary Shares	Dec. 31, 2012 Series A Preferred Stock	Mar. 31, 2013 March 2013 Repurchase Program	Sep. 30, 2013 March 2013 Repurchase Program	Dec. 31, 2013 March 2013 Repurchase Program	Mar. 31, 2013 March 2012 Share Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Amount of common stock authorized for repurchase												$ 2,100,000,000
Common stock acquired (shares)	31,200,000												24,700,000		6,500,000
Remaining authorized repurchase amount														420,000,000
Average cost per share of treasury shares repurchased (per share)	$ 65.30												$ 68.05		$ 54.95
Approximate aggregate cost of treasury shares repurchased	2,040,000,000												1,680,000,000		360,000,000
Cash dividends declared (in dollars per share)	$ 1.04	$ 0.96	$ 0.72
Common stock dividends	463,000,000	456,000,000	358,000,000		463,000,000	456,000,000	358,000,000
Shares purchased and held in trust	375,000	387,000
Preferred stock dividends (in dollars per share)								$ 5,250		$ 1.31
Depositary shares, ownership interest								0.025%
Preferred stock cash dividend	26,000,000	29,000,000	20,000,000		26,000,000	29,000,000	20,000,000		8,000,000		21,000,000
Liquidation preference (in dollars per share)								$ 100,000
Dividend rate								5.25%
Redemption price (in dollars per share)								$ 100,000		$ 25
Net gains (losses) from sales of available-for-sale securities	(14,000,000)
Unrealized pretax gains (losses) on securities included in AOCI		25,000,000	67,000,000	76,000,000
Deferred taxes on unrealized pretax gains (losses) on securities included in AOCI		10,000,000	27,000,000	30,000,000
Realized gains (losses) from sale of available-for-sale securities		$ 55,000,000	$ 140,000,000