Medicare Part D (Balance Sheet Amounts Associated With Medicare Part D) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Other current assets	$ 1,027.0	$ 632.0
Trade accounts payable and accrued expenses	(1,783.0)	(1,681.0)
Risk Corridor Settlement [Member]
Other current assets	2.0	1.0
Trade accounts payable and accrued expenses	(331.0)	(389.0)
Net current (liability) asset	(329.0)	(388.0)
CMS Subsidies/Discounts [Member]
Other current assets	363.0	16.0
Trade accounts payable and accrued expenses	(139.0)	(170.0)
Net current (liability) asset	$ 224.0	$ (154.0)