Selected Quarterly Financial Data (Unaudited) (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
Selected Quarterly Financial Data (Unaudited) disclosure
Total revenues	$ 6,783	$ 6,886	$ 6,785	$ 6,708	$ 6,737	$ 6,452	$ 6,674	$ 6,328	$ 27,162	$ 26,191	$ 25,740
Total expenses	5,323	5,628	5,884	5,238	5,366	5,275	5,497	5,108	22,073	21,246	22,574
Income before income taxes	1,460	1,258	901	1,470	1,371	1,177	1,177	1,220	5,089	4,945	3,166
Income tax expense	422	339	218	418	383	313	252	324	1,397	1,272	693
Net income	$ 1,038	$ 919	$ 683	$ 1,052	$ 988	$ 864	$ 925	$ 896	$ 3,692	$ 3,673	$ 2,473
Net income per share, basic	$ 3.15	$ 2.72	$ 1.98	$ 2.98	$ 2.73	$ 2.33	$ 2.44	$ 2.36	$ 10.82	$ 9.84	$ 6.35
Net income per share, diluted	$ 3.11	$ 2.69	$ 1.95	$ 2.95	$ 2.70	$ 2.30	$ 2.41	$ 2.33	$ 10.70	$ 9.74	$ 6.30