Preferred Stock Preferred Stock Summary (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended										9 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2013
Class of Stock [Line Items]
Total shares issued and outstanding (shares)			15,826						10,826		15,826
Carrying value			$ 1,562	[1]					$ 1,068	[1]	$ 1,562	[1]
Series A Noncumulative Perpetual Preferred Stock
Class of Stock [Line Items]
Per annum dividend rate											Greater of (i) three-month LIBOR plus 0.565% for the related distribution period; or (ii) 4.000%
Per annum dividend rate (percent)											4.00%
Liquidation preference per share (usd per share)			$ 100,000								$ 100,000
Total shares issued and outstanding (shares)			5,001						5,001		5,001
Carrying value			500	[1]					500	[1]	500	[1]
Dividends Payable, Date Declared			Jul. 17, 2013	[2],[3]	Apr. 09, 2013	[2],[3]	Jan. 16, 2013	[2],[3]
Dividends Payable, Date of Record			Sep. 05, 2013	[2],[3]	Jun. 05, 2013	[2],[3]	Mar. 05, 2013	[2],[3]
Preferred Stock Dividend Payment Date			Sep. 20, 2013	[2],[3]	Jun. 20, 2013	[2],[3]	Mar. 20, 2013	[2],[3]
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$ 10.1111	[2],[3]	$ 10.2222	[2],[3]	$ 10.2222	[2],[3]			$ 10.0000	[2],[3]
Series C Noncumulative Perpetual Preferred Stock
Class of Stock [Line Items]
Per annum dividend rate (percent)											5.20%
Liquidation preference per share (usd per share)			$ 100,000								$ 100,000
Total shares issued and outstanding (shares)			5,825						5,825		5,825
Carrying value			568	[1]					568	[1]	568	[1]
Dividends Payable, Date Declared			Jul. 17, 2013	[3],[4]	Apr. 09, 2013	[3],[4]	Jan. 16, 2013	[3],[4]
Dividends Payable, Date of Record			Sep. 05, 2013	[3],[4]	Jun. 05, 2013	[3],[4]	Mar. 05, 2013	[3],[4]
Preferred Stock Dividend Payment Date			Sep. 20, 2013	[3],[4]	Jun. 20, 2013	[3],[4]	Mar. 20, 2013	[3],[4]
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$ 0.3250	[3],[4]	$ 0.3250	[3],[4]	$ 0.3250	[3],[4]			$ 0.3250	[3],[4]
Series D Noncumulative Perpetual Preferred Stock
Class of Stock [Line Items]
Per annum dividend rate											4.50% commencing Dec. 20, 2013 to but excluding June 20, 2023, then a floating rate equal to the three-month LIBOR plus 2.46%
Per annum dividend rate (percent)											4.50%
Liquidation preference per share (usd per share)			$ 100,000								$ 100,000
Total shares issued and outstanding (shares)			5,000						0		5,000
Carrying value			$ 494	[1]					$ 0	[1]	$ 494	[1]
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$ 26.6250	[3],[4]
London Interbank Offered Rate (LIBOR) [Member] | Series A Noncumulative Perpetual Preferred Stock
Class of Stock [Line Items]
Preferred stock, basis spread on variable rate (percent)											0.565%
London Interbank Offered Rate (LIBOR) [Member] | Series D Noncumulative Perpetual Preferred Stock
Class of Stock [Line Items]
Preferred stock, basis spread on variable rate (percent)											2.46%
Scenario, Forecast [Member] | Series A Noncumulative Perpetual Preferred Stock
Class of Stock [Line Items]
Dividends Payable, Date Declared	Oct. 16, 2013	[2],[3]
Dividends Payable, Date of Record	Dec. 05, 2013	[2],[3]
Preferred Stock Dividend Payment Date	Dec. 20, 2013	[2],[3]
Scenario, Forecast [Member] | Series C Noncumulative Perpetual Preferred Stock
Class of Stock [Line Items]
Dividends Payable, Date Declared	Oct. 16, 2013	[3],[4]
Dividends Payable, Date of Record	Dec. 05, 2013	[3],[4]
Preferred Stock Dividend Payment Date	Dec. 20, 2013	[3],[4]
Scenario, Forecast [Member] | Series D Preferred Stock [Member]
Class of Stock [Line Items]
Dividends Payable, Date Declared	Oct. 16, 2013	[3],[5]
Dividends Payable, Date of Record	Dec. 05, 2013	[3],[5]
Preferred Stock Dividend Payment Date	Dec. 20, 2013	[3],[5]

[1] The carrying value of the Series C and Series D preferred stock is recorded net of issuance costs.

[2] Dividend per Normal Preferred Capital Security of Mellon Capital IV, each representing 1/100th interest in a share of Series A preferred stock.

[3] Dividends are noncumulative

[4] Dividend per depositary share, each representing a 1/4,000th interest in a share of Series C preferred stock.

[5]