Foreign Operations (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Foreign operations data
Revenues	$ 1,267.9	$ 1,166.8	$ 1,124.9
Identifiable assets	5,857.5	5,442.4	5,206.4
Foreign [Member]
Foreign operations data
Revenues	280.2	269.6	227.0
Identifiable assets	1,766.6	1,806.8	1,781.6
Foreign Operations (Textual) [Abstract]
Maximum percentage of consolidated revenues derive from any individual foreign country	10.00%	10.00%	10.00%
United States [Member]
Foreign operations data
Revenues	987.7	897.2	897.9
Identifiable assets	$ 4,090.9	$ 3,635.6	$ 3,424.8
Canada [Member]
Foreign Operations (Textual) [Abstract]
Percentage of company's identifiable assets	8.00%	10.00%	12.00%
Germany [Member]
Foreign Operations (Textual) [Abstract]
Percentage of company's identifiable assets	9.00%	10.00%