Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Consolidated Quarterly Results [Abstract]
Total revenues	$ 9,389	$ 8,757	$ 28,348	$ 25,986
Income before income taxes	878	818	2,668	2,572
Shareholders' net income	$ 547	$ 534	$ 1,668	$ 1,635
Shareholders' Net Income Per Share:
EPS, basic	$ 2.14	$ 2.04	$ 6.51	$ 6.16
EPS, diluted	2.10	2.01	6.40	6.05
Stock And Dividend Data [Abstract]
Dividends Declared Per Share	$ 0	$ 0	$ 0.04	$ 0.04