Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net income	$ 1,683	$ 2,448	$ 614
Adjustments to reconcile net income to net cash provided by operating activities:
Loss on sale of business	786	0	0
Net realized capital gains	(90)	(14)	(96)
Equity in net earnings of Kindred at Home	(11)	0	0
Stock-based compensation	137	157	115
Depreciation	444	410	388
Amortization	90	75	77
Provision (benefit) for deferred income taxes	194	132	(71)
Provision for doubtful accounts	36	20	39
Changes in operating assets and liabilities, net of effect of businesses acquired and dispositions:
Receivables	(200)	406	(158)
Other assets	(484)	(582)	426
Benefits payable	252	105	(413)
Other liabilities	(676)	641	937
Unearned revenues	(95)	98	(84)
Other	107	155	162
Net cash provided by operating activities	2,173	4,051	1,936
Cash flows from investing activities
Acquisitions, net of cash acquired	(354)	(31)	(7)
Acquisition, equity method investment in Kindred at Home	(1,095)	0	0
Cash transferred in sale of business	(805)	0	0
Purchases of property and equipment	(612)	(524)	(527)
Purchases of investment securities	(4,687)	(6,265)	(6,566)
Maturities of investment securities	972	1,111	1,426
Proceeds from sales of investment securities	3,494	2,768	4,312
Net cash used in investing activities	(3,087)	(2,941)	(1,362)
Cash flows from financing activities
(Withdrawals) receipts from contract deposits, net	(640)	1,823	1,093
Proceeds from issuance of senior notes, net	0	1,779	0
Proceeds from issuance (repayments) of commercial paper, net	485	(153)	(2)
Proceeds from term loan	1,000	0	0
Repayment of term loan	(350)	0	0
Repayment of long-term debt	0	(800)	0
Common stock repurchases	(1,090)	(3,365)	(104)
Dividends paid	(265)	(220)	(177)
Change in book overdraft	30	(71)	(89)
Proceeds from stock option exercises and other, net	45	62	11
Net cash (used in) provided by financing activities	(785)	(945)	732
(Decrease) increase in cash and cash equivalents	(1,699)	165	1,306
Cash and cash equivalents at beginning of year	4,042	3,877	2,571
Cash and cash equivalents at end of year	2,343	4,042	3,877
Supplemental cash flow disclosures:
Interest payments	195	216	185
Income tax payments, net	631	1,498	916
Details of businesses acquired in purchase transactions:
Fair value of assets acquired, net of cash acquired	392	31	7
Less: Fair value of liabilities assumed	(38)	0	0
Cash paid for acquired businesses, net of cash acquired	$ 354	$ 31	$ 7