Schedule II-Condensed Financial Information Of Registrant (Statement Of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities
Net income	$ 180.9	$ 654.8	$ 859.1	$ 865.2	$ 506.7	$ 630.9	$ 731.1	$ 701.0	$ 2,560.0	$ 2,569.7	$ 2,489.7
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized losses on investments									(157.5)	(177.0)	(271.9)
Other-than-temporary impairment losses recognized in income									83.4	49.0	98.9
(Gain) loss on extinguishment of debt									(9.3)	81.1	145.3
Loss on disposal of assets									16.0	(1.7)	3.9
Deferred income taxes									(65.9)	30.7	59.1
Amortization, net of accretion									802.1	744.5	800.9
Depreciation expense									105.8	106.5	107.9
Share-based compensation									148.2	168.9	146.0
Excess tax benefits from share-based compensation									(95.8)	(46.4)	(30.1)
Changes in operating assets and liabilities:
Receivables, net									(42.9)	(1,899.7)	(418.3)
Other invested assets, current									5.9	(21.7)	(15.1)
Other assets									33.8	405.5	(33.6)
Accounts payable and accrued expenses									(219.3)	(14.4)	303.6
Other liabilities									686.4	(7.9)	(154.6)
Income taxes									41.5	(34.0)	9.3
Other, net									(5.1)	(84.2)	(38.6)
Net cash provided by operating activities									4,116.0	3,369.3	3,052.3
Investing activities
Settlement of non-hedging derivatives									(36.5)	(67.4)	(109.8)
Changes in securities lending collateral									214.4	(545.6)	(405.1)
Other, net									(8.2)	(0.1)	1.3
Net cash provided by (used in) investing activities									(1,151.5)	(974.9)	(2,234.4)
Financing activities
Net proceeds from (repayments of) commercial paper borrowings									682.2	(379.2)	(191.7)
Proceeds from long-term borrowings									1,226.5	2,700.0	1,250.0
Repayments of long-term borrowings									(2,697.2)	(1,730.1)	(1,801.9)
Changes in securities lending payable									(214.4)	545.6	405.0
Changes in bank overdrafts									(243.8)	173.0	9.9
Premiums paid on equity call options									(16.7)	0.0	(25.8)
Proceeds from sale of put options									16.6	0.0	0.0
Repurchase and retirement of common stock									(1,515.8)	(2,998.8)	(1,620.1)
Cash dividends	(163.1)	$ (163.0)	$ (163.9)	(166.6)	(117.6)	$ (119.2)	$ (120.5)	(123.4)	(656.6)	(480.7)	(448.0)
Proceeds from issuance of common stock under employee stock plans									186.0	301.3	524.7
Excess tax benefits from share-based compensation									95.8	46.4	30.1
Net cash used in financing activities									(2,997.4)	(1,822.5)	(1,717.8)
Change in cash and cash equivalents									(38.2)	564.8	(897.7)
Cash and cash equivalents at beginning of year				2,151.7				1,582.1	2,151.7	1,582.1
Cash and cash equivalents at end of year	2,113.5				2,151.7				2,113.5	2,151.7	1,582.1
Anthem, Inc. [Member]
Operating activities
Net income									2,560.0	2,569.7	2,489.7
Adjustments to reconcile net income to net cash provided by operating activities:
(Undistributed) distributed earnings of subsidiaries									(287.8)	244.3	(78.5)
Net realized losses on investments									3.8	27.1	83.2
Other-than-temporary impairment losses recognized in income									39.2	28.5	51.4
(Gain) loss on extinguishment of debt									(9.3)	81.1	145.3
Loss on disposal of assets									0.2	3.9	3.6
Deferred income taxes									55.0	52.7	(4.5)
Amortization, net of accretion									40.8	17.5	25.2
Depreciation expense									68.1	67.4	45.7
Share-based compensation									148.2	168.9	146.0
Excess tax benefits from share-based compensation									(95.8)	(46.4)	(30.1)
Changes in operating assets and liabilities:
Receivables, net									(17.9)	(16.6)	3.5
Other invested assets, current									(0.2)	(3.8)	(0.3)
Other assets									(106.9)	55.6	42.3
Amounts due from/to subsidiaries									420.5	566.1	(983.1)
Accounts payable and accrued expenses									7.5	(111.4)	111.8
Other liabilities									(231.4)	(113.8)	(18.6)
Income taxes									47.2	(36.0)	83.9
Other, net									(10.2)	0.0	0.0
Net cash provided by operating activities									2,631.0	3,554.8	2,116.5
Investing activities
Purchases of investments									(2,130.7)	(1,819.3)	(1,964.3)
Proceeds from sales, maturities, calls and redemptions of investments									3,076.6	820.7	2,443.3
Settlement of non-hedging derivatives									(36.5)	(67.4)	(109.8)
Capitalization of subsidiaries									(939.7)	(321.8)	(121.2)
Changes in securities lending collateral									94.0	(178.8)	(17.0)
Purchases of property and equipment, net of sales									(51.1)	(57.0)	(87.4)
Other, net									1.5	(38.0)	(18.9)
Net cash provided by (used in) investing activities									14.1	(1,661.6)	124.7
Financing activities
Net proceeds from (repayments of) commercial paper borrowings									682.2	(379.2)	(191.7)
Proceeds from long-term borrowings									1,226.5	2,700.0	1,250.0
Repayments of long-term borrowings									(2,697.2)	(1,730.1)	(1,245.0)
Changes in securities lending payable									(94.2)	178.6	17.1
Changes in bank overdrafts									(89.3)	55.5	71.8
Premiums paid on equity call options									(16.7)	0.0	(25.8)
Proceeds from sale of put options									16.6	0.0	0.0
Repurchase and retirement of common stock									(1,515.8)	(2,998.8)	(1,620.1)
Cash dividends									(686.5)	(501.6)	(465.9)
Proceeds from issuance of common stock under employee stock plans									186.0	301.3	524.7
Excess tax benefits from share-based compensation									95.8	46.4	30.1
Net cash used in financing activities									(2,892.6)	(2,327.9)	(1,654.8)
Change in cash and cash equivalents									(247.5)	(434.7)	586.4
Cash and cash equivalents at beginning of year				$ 739.8				$ 1,174.5	739.8	1,174.5	588.1
Cash and cash equivalents at end of year	$ 492.3				$ 739.8				$ 492.3	$ 739.8	$ 1,174.5