Intangible Assets (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Intangible Assets [Abstract]
Amortization expense on intangible assets	$ 5.5	$ 7.2
Estimated amortization expense, 2012	14.6
Estimated amortization expense, 2013	14.5
Estimated amortization expense, 2014	12.2
Estimated amortization expense, 2015	10.4
Estimated amortization expense, 2016	$ 8.9