Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Consolidated Results
Total revenues	$ 11,380	$ 10,474
Income (loss) before income taxes	1,218	890
Shareholders' net income	$ 915	$ 598
Shareholders' Net Income Per Share:
EPS, basic	$ 3.78	$ 2.34
EPS, diluted	3.72	2.3
Stock and Dividend Data
Dividends Declared Per Share	$ 0.04	$ 0.04
Special items
Long-term care guaranty fund assessment	$ 0	$ 83
Transaction-related costs	50	49
Total impact of special items, after-tax	$ 50	$ 132