CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 224.0	$ 193.6
Other comprehensive income (loss):
Foreign currency translation gain	29.1	12.2
Change in net realized and unrealized gain (loss) on derivative securities, net of tax	0.3	(0.3)
Change in net unrealized gain on investment securities, net of tax	0.0	4.9
Other comprehensive income	29.4	16.8
Comprehensive income	253.4	210.4
Comprehensive income (non-controlling interests)	(79.5)	(73.7)
Comprehensive income (controlling interest)	$ 173.9	$ 136.7