Condensed Consolidated Statements Of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities
Net income	$ 491	$ 1,115
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized capital gains	(29)	(26)
Stock-based compensation	35	26
Depreciation	109	100
Other intangible amortization	30	18
Provision for deferred income taxes	83	29
Changes in operating assets and liabilities, net of effect of businesses acquired and dispositions:
Receivables	(422)	(558)
Other assets	(1,164)	(415)
Benefits payable	293	198
Other liabilities	885	542
Unearned revenues	3,328	3,140
Other, net	47	36
Net cash provided by operating activities	3,686	4,205
Cash flows from investing activities
Acquisitions, net of cash acquired	(169)	(7)
Purchases of property and equipment	(134)	(122)
Purchases of investment securities	(1,711)	(1,876)
Maturities of investment securities	217	284
Proceeds from sales of investment securities	1,392	795
Net cash used in investing activities	(405)	(926)
Cash flows from financing activities
Receipts from contract deposits, net	1,401	1,730
Proceeds from issuance of senior notes, net	0	991
Proceeds from issuance of commercial paper, net	245	169
Change in book overdraft	(17)	(34)
Common stock repurchases	(51)	(1,574)
Dividends paid	(57)	(47)
Proceeds from stock option exercises and other	11	34
Net cash provided by financing activities	1,532	1,269
Increase in cash and cash equivalents	4,813	4,548
Cash and cash equivalents at beginning of period	4,042	3,877
Cash and cash equivalents at end of period	8,855	8,425
Supplemental cash flow disclosures:
Interest payments	22	10
Income tax payments (refunds), net	$ 4	$ (4)