Consolidated Statements of Comprehensive Income (Parentheticals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Comprehensive Income (Loss), Tax, Parenthetical Disclosures [Abstract]
Foreign currency translation gain (loss), tax (expense) benefit	$ (11.4)	$ 9.8	$ 85.4
Net actuarial gain (loss) and prior service cost, tax (expense) benefit	(2.1)	3.1	1.0
Realized gain on interest rate swap, tax (expense) benefit	(0.7)	(1.0)	(0.6)
Net gain (loss) on marketable securities held in trust fund, tax (expense) benefit	$ (1.0)	$ 3.3	$ 0.0