Schedule II-Condensed Financial Information Of Registrant (Statement Of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net income	$ 368.4	$ 617.8	$ 780.6	$ 703.0	$ 180.9	$ 654.8	$ 859.1	$ 865.2	$ 2,469.8	$ 2,560.0	$ 2,569.7
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized losses on financial instruments									(220.1)	(147.1)	(240.3)
Other-than-temporary impairment losses recognized in income									115.4	83.4	49.0
(Gain) loss on extinguishment of debt									0.0	(9.3)	81.1
Loss on disposal of assets									4.5	16.0	(1.7)
Deferred income taxes									126.9	(65.9)	30.7
Amortization, net of accretion									807.8	802.1	744.5
Depreciation expense									104.0	105.8	106.5
Share-based compensation									164.6	148.2	168.9
Excess tax benefits from share-based compensation									(53.5)	(95.8)	(46.4)
Changes in operating assets and liabilities:
Receivables, net									(1,380.5)	(42.9)	(1,899.7)
Other invested assets, current									(19.4)	5.9	(21.7)
Other assets									(127.7)	33.8	405.5
Accounts payable and accrued expenses									116.6	(219.3)	(14.4)
Other liabilities									605.7	686.4	(7.9)
Other, net									(96.5)	(5.1)	(84.2)
Net cash provided by operating activities									3,204.5	4,116.0	3,369.3
Investing activities
Changes in collateral and settlement of non-hedging derivatives									(34.5)	(36.5)	(67.4)
Changes in securities lending collateral									222.0	214.4	(545.6)
Other, net									(3.0)	(8.2)	(0.1)
Net cash used in investing activities									(513.9)	(1,151.5)	(974.9)
Financing activities
Net (repayments of) proceeds from commercial paper borrowings									(53.2)	682.2	(379.2)
Proceeds from long-term borrowings									0.0	1,226.5	2,700.0
Repayments of long-term borrowings									0.0	(2,697.2)	(1,730.1)
Changes in securities lending payable									(222.0)	(214.4)	545.6
Changes in bank overdrafts									513.8	(243.8)	173.0
Premiums paid on equity call options									0.0	(16.7)	0.0
Proceeds from sale of put options									0.0	16.6	0.0
Repurchase and retirement of common stock									0.0	(1,515.8)	(2,998.8)
Change in collateral and settlements of debt-related derivatives									(360.4)	0.0	0.0
Cash dividends	(171.3)	$ (171.1)	$ (170.9)	(170.7)	(163.1)	$ (163.0)	$ (163.9)	(166.6)	(684.0)	(656.6)	(480.7)
Proceeds from issuance of common stock under employee stock plans									119.4	186.0	301.3
Excess tax benefits from share-based compensation									53.5	95.8	46.4
Net cash used in financing activities									(732.9)	(2,997.4)	(1,822.5)
Change in cash and cash equivalents									1,961.8	(38.2)	564.8
Cash and cash equivalents at beginning of year				2,113.5				2,151.7	2,113.5	2,151.7
Cash and cash equivalents at end of year	4,075.3				2,113.5				4,075.3	2,113.5	2,151.7
Anthem, Inc. [Member]
Operating activities
Net income									2,469.8	2,560.0	2,569.7
Adjustments to reconcile net income to net cash provided by operating activities:
(Undistributed) distributed earnings of subsidiaries									(502.4)	(287.8)	244.3
Net realized losses on financial instruments									195.0	3.8	27.1
Other-than-temporary impairment losses recognized in income									47.8	39.2	28.5
(Gain) loss on extinguishment of debt									0.0	(9.3)	81.1
Loss on disposal of assets									2.3	0.2	3.9
Deferred income taxes									(7.0)	55.0	52.7
Amortization, net of accretion									33.5	40.8	17.5
Depreciation expense									70.4	68.1	67.4
Share-based compensation									164.6	148.2	168.9
Excess tax benefits from share-based compensation									(53.5)	(95.8)	(46.4)
Changes in operating assets and liabilities:
Receivables, net									17.5	(17.9)	(16.6)
Other invested assets, current									1.3	(0.2)	(3.8)
Other assets									213.2	(106.9)	55.6
Amounts due from/to subsidiaries									(1,487.8)	420.5	566.1
Accounts payable and accrued expenses									(21.8)	7.5	(111.4)
Other liabilities									(30.7)	(231.4)	(113.8)
Income taxes									198.4	47.2	(36.0)
Other, net									5.1	(10.2)	0.0
Net cash provided by operating activities									1,315.7	2,631.0	3,554.8
Investing activities
Purchases of investments									(2,874.9)	(2,130.7)	(1,819.3)
Proceeds from sales, maturities, calls and redemptions of investments									3,309.8	3,076.6	820.7
Changes in collateral and settlement of non-hedging derivatives									(34.5)	(36.5)	(67.4)
Capitalization of subsidiaries									(295.0)	(939.7)	(321.8)
Changes in securities lending collateral									91.8	94.0	(178.8)
Purchases of property and equipment, net of sales									(98.7)	(51.1)	(57.0)
Other, net									(7.9)	1.5	(38.0)
Net cash used in investing activities									90.6	14.1	(1,661.6)
Financing activities
Net (repayments of) proceeds from commercial paper borrowings									(53.2)	682.2	(379.2)
Proceeds from long-term borrowings									0.0	1,226.5	2,700.0
Repayments of long-term borrowings									0.0	(2,697.2)	(1,730.1)
Changes in securities lending payable									(90.9)	(94.2)	178.6
Changes in bank overdrafts									30.8	(89.3)	55.5
Premiums paid on equity call options									0.0	(16.7)	0.0
Proceeds from sale of put options									0.0	16.6	0.0
Repurchase and retirement of common stock									0.0	(1,515.8)	(2,998.8)
Change in collateral and settlements of debt-related derivatives									(360.4)	0.0	0.0
Cash dividends									(715.1)	(686.5)	(501.6)
Proceeds from issuance of common stock under employee stock plans									119.4	186.0	301.3
Excess tax benefits from share-based compensation									53.5	95.8	46.4
Net cash used in financing activities									(1,015.9)	(2,892.6)	(2,327.9)
Change in cash and cash equivalents									390.4	(247.5)	(434.7)
Cash and cash equivalents at beginning of year				$ 492.3				$ 739.8	492.3	739.8	1,174.5
Cash and cash equivalents at end of year	$ 882.7				$ 492.3				$ 882.7	$ 492.3	$ 739.8