Quarterly Financial Information (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Quarterly Financial Information [Abstract]
Net Revenues	$ 1,551		$ 1,551		$ 1,478		$ 1,478		$ 1,435		$ 1,373		$ 1,337		$ 1,290		$ 6,058		$ 5,435		$ 4,883
Expenses Excluding Interest	997		1,033		957		956		937		909		925		959		3,943	[1]	3,730	[1]	3,433	[1]
Net Income	350		321		324		326		319		290		256		206		1,321		1,071		928
Net Income Available to Common Stockholders	$ 329		$ 312		$ 302		$ 318		$ 297		$ 282		$ 233		$ 198		$ 1,261		$ 1,010		$ 883
Weighted Average Common Shares Outstanding - Diluted	1,320		1,316		1,313		1,311		1,304		1,296		1,288		1,282		1,315	[2]	1,293	[2]	1,275	[2]
Earnings Per Common Share - Basic	$ 0.25		$ 0.24		$ 0.23		$ 0.24		$ 0.23		$ 0.22		$ 0.18		$ 0.15		$ 0.96		$ 0.78		$ 0.69
Earnings Per Common Share - Diluted	$ 0.25		$ 0.24		$ 0.23		$ 0.24		$ 0.23		$ 0.22		$ 0.18		$ 0.15		$ 0.95		$ 0.78		$ 0.69
Dividends Declared Per Common Share	$ 0.06		$ 0.06		$ 0.06		$ 0.06		$ 0.06		$ 0.06		$ 0.06		$ 0.06		$ 0.24		$ 0.24		$ 0.24
Range of Common Stock Price Per Share:
High	$ 30.89		$ 31.00		$ 28.04		$ 29.13		$ 26.00		$ 22.69		$ 21.23		$ 18.11
Low	$ 23.35		$ 26.44		$ 24.56		$ 23.56		$ 20.57		$ 20.74		$ 16.21		$ 15.05
Range of Price/Earnings Ratio:
High	32	[3]	33	[3]	30	[3]	33	[3]	33	[3]	32	[3]	32	[3]	26	[3]
Low	24	[3]	28	[3]	27	[3]	27	[3]	26	[3]	30	[3]	24	[3]	22	[3]

[1] Unallocated amount includes a charge of $68 million for estimated future severance benefits resulting from changes in the Company’s geographic footprint in 2014.

[2] Antidilutive stock options and restricted stock awards excluded from the calculation of diluted EPS totaled 24 million, 34 million, and 74 million shares in 2014, 2013, and 2012, respectively.

[3] Price/earnings ratio is computed by dividing the high and low market prices by diluted earnings per common share for the preceding 12-month period ending on the last day of the quarter presented.