Segment Information Balance Sheet (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Segments:
Assets	$ 12,876.6	$ 13,070.8
IAN
Segments:
Assets	10,589.2	10,481.7
CMG
Segments:
Assets	1,019.9	930.5
Corporate and other
Segments:
Assets	$ 1,267.5	$ 1,658.6