Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Consolidated Quarterly Results [Abstract]
Total revenues	$ 9,492	$ 8,733	$ 18,959	$ 17,229
Income before income taxes	936	901	1,790	1,754
Shareholders' net income	$ 588	$ 573	$ 1,121	$ 1,101
Shareholders' Net Income Per Share:
EPS, basic	$ 2.30	$ 2.16	$ 4.38	$ 4.11
EPS, diluted	2.26	2.12	4.30	4.05
Stock And Dividend Data [Abstract]
Dividends Declared Per Share	$ 0	$ 0	$ 0.04	$ 0.04