Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010
Commitments and Contingencies
Total rental expense under operating leases	$ 21.6	$ 18.5	$ 15.8
Future minimum lease payments under non-cancelable operating leases
2013	19.4
2014	16.1
2015	13.5
2016	10.7
2017	8.8
Thereafter	16.7
Total	85.2
Capital Leases
Cost of the buildings under the capital leases	9.9	9.9
Accumulated amortization of the leased buildings	3.0	2.6
License Agreements
Income from cross-licensing agreements	20.2	2.9	3.2
Royalties payable, if patents are used in connection with a commercial product sale, low end of range (as a percent)	0.15%
Royalties payable, if patents are used in connection with a commercial product sale, high end of range (as a percent)	5.00%
Licensing fees	4.2	2.8	1.8
Grants
Amounts received under grants from government authorities in the U.S. and Germany	4.7	4.0	3.8
Total expenditures related to government grants	$ 5.1	$ 5.5	$ 4.5
Legal
Current employee	1
Former employee	1