Schedule II-Condensed Financial Information Of Registrant (Statements Of Income) (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
Net investment income									$ 779.5	$ 677.6	$ 724.4
Net realized losses on financial instruments									220.1	147.1	240.3
Total other-than-temporary impairment losses on investments									(147.1)	(99.9)	(56.2)
Portion of other-than-temporary impairment losses recognized in other comprehensive income									31.7	16.5	7.2
Other-than-temporary impairment losses recognized in income									(115.4)	(83.4)	(49.0)
Other revenue									35.1	43.1	41.3
Total revenues (losses)	$ 21,714.4	$ 21,403.9	$ 21,456.2	$ 20,288.5	$ 20,187.9	$ 19,901.6	$ 20,015.5	$ 19,051.5	84,863.0	79,156.5	73,874.1
General and administrative expense									11,166.4	11,093.7	10,258.3
Interest expense									723.0	653.0	600.7
(Gain) loss on extinguishment of debt									0.0	(9.3)	81.1
Loss before income tax credits and equity in net income of subsidiaries									4,555.4	4,631.0	4,368.1
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
Anthem, Inc. [Member]
Net investment income									74.7	99.7	87.4
Net realized losses on financial instruments									(195.0)	(3.8)	(27.1)
Total other-than-temporary impairment losses on investments									(65.0)	(49.2)	(35.5)
Portion of other-than-temporary impairment losses recognized in other comprehensive income									17.2	10.0	7.0
Other-than-temporary impairment losses recognized in income									(47.8)	(39.2)	(28.5)
Other revenue									0.0	3.5	4.8
Total revenues (losses)									(168.1)	60.2	36.6
General and administrative expense									270.0	77.9	20.3
Interest expense									719.3	649.7	597.8
(Gain) loss on extinguishment of debt									0.0	(9.3)	81.1
Total expenses									989.3	718.3	699.2
Loss before income tax credits and equity in net income of subsidiaries									(1,157.4)	(658.1)	(662.6)
Income tax credits									(438.5)	(270.1)	(255.4)
Equity in net income of subsidiaries									3,188.7	2,948.0	2,976.9
Net income									$ 2,469.8	$ 2,560.0	$ 2,569.7