Operating Segments (Details 2) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
U.S. Other Services
Financial information of reportable segments
Total service revenue	$ 101.2	$ 100.1	$ 288.6	$ 285.7
International
Financial information of reportable segments
Total service revenue	$ 51.5	$ 45.5	$ 151.7	$ 134.8