Supplemental Disclosures (Schedule of Supplemental Cash Flow Disclosures) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Supplemental Cash Flow Information [Abstract]
Assets acquired, excluding cash	$ 214	$ 867	$ 420
Liabilities assumed	(21)	(176)	(24)
Shares issued (7.6 million and 10.7 million shares in 2010 and 2009, respectively)	0	(183)	(229)
Contingent/deferred purchase consideration	(33)	(81)	(100)
Net cash outflow for current year acquisitions	160	427	67
Purchase of other intangibles	4	3	0
Contingent payments from prior years' acquisitions	0	2	6
Deferred purchase consideration from prior years' acquisitions	11	60	0
Subtotal	175	492	73
Cash paid into escrow for future acquisition	62	0	0
Net cash outflow for acquisitions	237	492	73
Interest paid	188	232	230
Income taxes paid, net of refunds	$ 37	$ 39	$ 219
Shares issued	0	7.6	10.7