Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Foreign currency translation adjustment, tax	$ (7.2)	$ (7.3)	$ (4.3)
Unrealized gain (loss) on derivatives, tax	(0.6)	0.6	1.7
Unrealized gain on available-for-sale investments, tax	$ (0.1)	$ 0.1	$ 0.1