Condensed Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities
Net income	$ 893	$ 604
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized capital gains	(10)	(14)
Stock-based compensation	51	54
Depreciation and amortization	206	160
Benefit for deferred income taxes	(8)	(9)
Changes in operating assets and liabilities, net of effect of businesses acquired:
Receivables	(860)	177
Other assets	(108)	(250)
Benefits payable	378	170
Other liabilities	52	51
Unearned revenues	(37)	2,077
Other, net	28	32
Net cash provided by operating activities	585	3,052
Cash flows from investing activities
Acquisitions, net of cash acquired	(12)	(76)
Proceeds from sale of business	33	0
Purchases of property and equipment	(187)	(185)
Purchases of investment securities	(1,385)	(1,364)
Maturities of investment securities	549	757
Proceeds from sales of investment securities	854	529
Net cash used in investing activities	(148)	(339)
Cash flows from financing activities
Receipts (withdrawals) from contract deposits, net	132	152
Repayment of long-term debt	0	(36)
Change in book overdraft	(78)	(46)
Common stock repurchases	(231)	(278)
Dividends paid	(83)	(82)
Excess tax benefit from stock-based compensation	0	21
Proceeds from stock option exercises and other	36	48
Net cash used in financing activities	(224)	(221)
Increase in cash and cash equivalents	213	2,492
Cash and cash equivalents at beginning of period	1,306	1,377
Cash and cash equivalents at end of period	1,519	3,869
Supplemental cash flow disclosures:
Interest payments	72	55
Income tax payments, net	$ 511	$ 293