Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Net premiums, principally supplemental health insurance		$ 18,531	$ 19,225	$ 17,570
Net investment income		3,220	3,278	3,135
Realized investment gains (losses):
Other-than-temporary impairment losses realized		(37)	(85)	(154)
Sales and redemptions		28	141	302
Derivative and other gains (losses)		(142)	(70)	(42)
Total realized investment gains (losses)		(151)	(14)	106
Other income (loss)		67	70	61
Total revenues		21,667	22,559	20,872
Benefits and expenses:
Benefits and claims, net		12,181	12,919	11,746
Acquisition and operating expenses:
Amortization of deferred policy acquisition costs		1,132	1,141	1,066
Insurance commissions		1,316	1,368	1,303
Insurance and other expenses	[1]	2,780	2,796	2,606
Interest expense		240	268	289
Total acquisition and operating expenses		5,468	5,573	5,264
Total benefits and expenses		17,649	18,492	17,010
Earnings before income taxes		4,018	4,067	3,862
Income Tax Expense:
Current		631	884	1,288
Deferred		(1,217)	524	41
Total income tax expense		(586)	1,408	1,329
Net earnings		$ 4,604	$ 2,659	$ 2,533
Net earnings per share:
Basic (in dollars per share)		$ 11.63	$ 6.46	$ 5.88
Diluted (in dollars per share)		$ 11.54	$ 6.42	$ 5.85
Weighted-average outstanding common shares used in computing earnings per share (In thousands):
Basic (in shares)		396,021	411,471	430,654
Diluted (in shares)		398,930	413,921	433,172
5.50% subordinated notes due September 2052
Expense on extinguishment of debt		$ 13
Senior Notes due 2039 and 2040
Expense on extinguishment of debt			$ 137
8.50% senior notes due May 2019
Expense on extinguishment of debt				$ 230

[1] Includes expense of $13 in 2017, $137 in 2016 and $230 in 2015 for the early extinguishment of debt