Schedule II-Condensed Financial Information Of Registrant (Statements Of Income) (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
Net investment income									$ 677.6	$ 724.4	$ 659.1
Net realized losses on investments									157.5	177.0	271.9
Total other-than-temporary impairment losses on investments									(99.9)	(56.2)	(100.6)
Portion of other-than-temporary impairment losses recognized in other comprehensive income									16.5	7.2	1.7
Other-than-temporary impairment losses recognized in income									(83.4)	(49.0)	(98.9)
Other revenue									43.1	41.3	40.4
Total revenues (losses)	$ 20,187.9	$ 19,901.6	$ 20,015.5	$ 19,051.5	$ 18,984.3	$ 18,557.0	$ 18,473.4	$ 17,859.4	79,156.5	73,874.1	71,023.5
General and administrative expense									11,093.7	10,258.3	8,426.0
Interest expense									653.0	600.7	602.7
(Gain) loss on extinguishment of debt									(9.3)	81.1	145.3
Loss before income tax credits and equity in net income of subsidiaries									4,631.0	4,368.1	3,840.2
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
Anthem, Inc. [Member]
Net investment income									99.7	87.4	61.2
Net realized losses on investments									(3.8)	(27.1)	(83.2)
Total other-than-temporary impairment losses on investments									(49.2)	(35.5)	(51.6)
Portion of other-than-temporary impairment losses recognized in other comprehensive income									10.0	7.0	0.2
Other-than-temporary impairment losses recognized in income									(39.2)	(28.5)	(51.4)
Other revenue									3.5	4.8	4.4
Total revenues (losses)									60.2	36.6	(69.0)
General and administrative expense									77.9	20.3	196.6
Interest expense									649.7	597.8	598.4
(Gain) loss on extinguishment of debt									(9.3)	81.1	145.3
Total expenses									718.3	699.2	940.3
Loss before income tax credits and equity in net income of subsidiaries									(658.1)	(662.6)	(1,009.3)
Income tax credits									(270.1)	(255.4)	(369.7)
Equity in net income of subsidiaries									2,948.0	2,976.9	3,129.3
Net income									$ 2,560.0	$ 2,569.7	$ 2,489.7