Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues
Net earned premiums	$ 6,988	$ 6,924	$ 6,921
Net investment income	2,034	1,988	1,840
Net realized investment gains (losses):
Other-than-temporary impairment losses	(14)	(81)	(156)
Other net realized investment gains	107	131	89
Net realized investment gains (losses)	93	50	(67)
Other revenues	427	404	407
Total revenues	9,542	9,366	9,101
Claims, Benefits and Expenses
Insurance claims and policyholders’ benefits	5,310	5,283	5,384
Amortization of deferred acquisition costs	1,233	1,235	1,540
Other operating expenses	1,528	1,552	1,473
Interest	161	159	155
Total claims, benefits and expenses	8,232	8,229	8,552
Income before income tax	1,310	1,137	549
Income tax expense	(411)	(278)	(70)
Net income	$ 899	$ 859	$ 479
Basic earnings per share
Basic earnings (loss) per share (in usd per share)	$ 3.32	$ 3.18	$ 1.77
Diluted earnings per share
Diluted earnings (loss) per share (in usd per share)	3.30	3.17	1.77
Dividends declared per share (in usd per share)	$ 3.1	$ 3	$ 3
Weighted Average Outstanding Common Stock and Common Stock Equivalents
Basic (in shares)	271.1	270.4	270.2
Diluted (in shares)	272.1	271.1	270.7