Business Segment Information (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenue and property, plant and equipment by geographical area
Total revenue	$ 475.1	$ 418.4	$ 401.2	$ 357.0	$ 416.1	$ 310.2	$ 300.9	$ 277.7	$ 1,651.7	$ 1,304.9	$ 1,114.5
Total property, plant and equipment	249.0				233.7				249.0	233.7
United States
Revenue and property, plant and equipment by geographical area
Total revenue									309.2	264.0	209.2
Total property, plant and equipment	44.9				40.0				44.9	40.0
Germany
Revenue and property, plant and equipment by geographical area
Total revenue									195.3	181.6	192.2
Total property, plant and equipment	132.2				126.0				132.2	126.0
Rest of Europe
Revenue and property, plant and equipment by geographical area
Total revenue									483.2	384.1	340.8
Total property, plant and equipment	60.3				59.2				60.3	59.2
Asia Pacific
Revenue and property, plant and equipment by geographical area
Total revenue									500.7	342.7	264.9
Total property, plant and equipment	7.3				5.6				7.3	5.6
Other
Revenue and property, plant and equipment by geographical area
Total revenue									163.3	132.5	107.4
Total property, plant and equipment	$ 4.3				$ 2.9				$ 4.3	$ 2.9