Schedule II-Condensed Financial Information Of Registrant (Balance Sheets (Parenthetical)) (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Available-for-sale fixed maturity securities investments, current, amortized cost	$ 16,950.0	$ 17,120.4
Available-for-sale equity securities investments, current, cost	1,055.8	1,303.7
Available-for-sale fixed maturity securities investments, long-term, amortized cost	550.4	500.7
Available-for-sale equity securities investments, long-term, cost	$ 27.3	$ 27.0
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	900,000,000	900,000,000
Common stock, shares issued	261,238,188	268,109,932
Common stock, shares outstanding	261,238,188	268,109,932
Anthem, Inc. [Member]
Available-for-sale fixed maturity securities investments, current, amortized cost	$ 889.6	$ 1,798.8
Available-for-sale equity securities investments, current, cost	53.0	148.7
Available-for-sale equity securities investments, long-term, cost	$ 6.5	$ 6.6
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	900,000,000	900,000,000
Common stock, shares issued	261,238,188	268,109,932
Common stock, shares outstanding	261,238,188	268,109,932