Segment Information Balance Sheet (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Segments:
Assets	$ 11,728.7	$ 12,876.6
IAN
Segments:
Assets	10,276.9	10,589.2
CMG
Segments:
Assets	1,091.7	1,019.9
Corporate and other
Segments:
Assets	$ 360.1	$ 1,267.5