Goodwill And Other Intangible Assets (Components Of Other Intangible Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Intangible Assets [Line Items]
Gross Carrying Amount, Finite Lived Intangibles	$ 3,636.0	$ 3,520.9
Accumulated Amortization, Finite Lived Intangibles	(2,768.3)	(2,558.1)
Net Carrying Amount, Finite Lived Intangibles	867.7	962.8
Gross Carrying Amount, Indefinite Lived Intangibles	7,290.3	6,995.3
Net Carrying Amount, Indefinite Lived Intangibles	7,290.3	6,995.3
Gross Carrying Amount, Total Intangible Assets	10,926.3	10,516.2
Accumulated Amortization, Total Intangible Assets	(2,768.3)	(2,558.1)
Net Carrying Amount, Total Intangible Assets	8,158.0	7,958.1
Blue Cross And Blue Shield And Other Trademarks [Member]
Intangible Assets [Line Items]
Gross Carrying Amount, Indefinite Lived Intangibles	6,298.7	6,298.7
Net Carrying Amount, Indefinite Lived Intangibles	6,298.7	6,298.7
State Medicaid Licenses [Member]
Intangible Assets [Line Items]
Gross Carrying Amount, Indefinite Lived Intangibles	991.6	696.6
Net Carrying Amount, Indefinite Lived Intangibles	991.6	696.6
Customer Relationships [Member]
Intangible Assets [Line Items]
Gross Carrying Amount, Finite Lived Intangibles	3,394.4	3,318.4
Accumulated Amortization, Finite Lived Intangibles	(2,670.0)	(2,473.4)
Net Carrying Amount, Finite Lived Intangibles	724.4	845.0
Provider And Hospital Relationships [Member]
Intangible Assets [Line Items]
Gross Carrying Amount, Finite Lived Intangibles	150.9	140.9
Accumulated Amortization, Finite Lived Intangibles	(58.6)	(51.4)
Net Carrying Amount, Finite Lived Intangibles	92.3	89.5
Other [Member]
Intangible Assets [Line Items]
Gross Carrying Amount, Finite Lived Intangibles	90.7	61.6
Accumulated Amortization, Finite Lived Intangibles	(39.7)	(33.3)
Net Carrying Amount, Finite Lived Intangibles	$ 51.0	$ 28.3