Financial Instruments (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Derivative instruments
Percentage of projected intercompany purchases hedged by forward exchange contracts	50.00%
Period of projected intercompany purchase transactions	12 months
Notional amounts of foreign currency purchase contracts	$ 4.5
Amount of Gain or (Loss) Recognized in Income on Derivatives
Income (loss) from derivatives recorded to other expense (income), net in statement of operations	0.1	0.6	0.5
High end of range
Derivative instruments
Average volume of foreign currency contracts	15
Low end of range
Derivative instruments
Average volume of foreign currency contracts	$ 5