Fair Value Measurements (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Fair value of assets and liabilities measured on recurring basis
Short-term investments	$ 30.7	$ 23.2
Forward contracts	7.0	3.3
Total	37.7	26.5
Fair value measurements recurring basis | Level 1
Fair value of assets and liabilities measured on recurring basis
Short-term investments	30.7	23.2
Total	30.7	23.2
Fair value measurements recurring basis | Level 2
Fair value of assets and liabilities measured on recurring basis
Forward contracts	7.0	3.3
Total	$ 7.0	$ 3.3