Commitments and Contingencies Long-term Operating lease commitments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating lease commitments [Abstract]
Operating Leases, Rent Expense	$ 7.3	$ 5.0	$ 4.5
Operating Leases, Future Minimum Payments Due, Next Twelve Months	6.7
Operating Leases, Future Minimum Payments, Due in Two Years	6.5
Operating Leases, Future Minimum Payments, Due in Three Years	6.6
Operating Leases, Future Minimum Payments, Due in Four Years	6.5
Operating Leases, Future Minimum Payments, Due in Five Years	6.7
Operating Leases, Future Minimum Payments, Due Thereafter	$ 29.1