Supplemental Disclosures (Schedule of Supplemental Cash Flow Disclosures) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplemental Cash Flow Information [Abstract]
Assets acquired, excluding cash		$ 217	$ 380	$ 214
Released from escrow in 2012	(62)	0	(62)	0
Liabilities assumed		(53)	(42)	(21)
Contingent/deferred purchase consideration		(39)	(46)	(33)
Net cash outflow for current year acquisitions		125	230	160
Purchase of other intangibles		2	3	4
Deferred purchase consideration from prior years' acquisitions		15	59	11
Subtotal		142	292	175
Cash paid into escrow for future acquisition		0	0	62
Net cash outflow for acquisitions		142	292	237
Interest paid		170	183	188
Income taxes paid, net of refunds		$ 360	$ 350	$ 37