Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 257.8	$ 345.0	$ 566.9
Available-for-sale debt securities:
Change in net unrealized gains and losses, net of tax (provision) benefit of $(1.9), $(1.0), and $1.0 for 2020, 2019, and 2018, respectively	5.7	4.6	0.6
Net realized (gains) losses reclassified into net income, net of tax	(1.3)	(0.4)	0.9
Net change on available-for-sale debt securities, net of tax	4.4	4.2	1.5
Cash flow hedges:
Change in net unrealized gains and losses, net of tax (provision) benefit of $(9.1), $(2.6), and $2.3 for 2020, 2019, and 2018, respectively	54.4	(8.9)	(6.4)
Net realized losses (gains) reclassified into net income, net of tax benefit (provisions) of $1.4, $(1.7), and $(0.3) for 2020, 2019, and 2018, respectively	7.6	5.5	(1.2)
Net change on cash flow hedges, net of tax	62.0	(3.4)	(7.6)
Change in foreign currency translation adjustments	7.7	(1.1)	(12.4)
Other comprehensive income (loss), net	74.1	(0.3)	(18.5)
Comprehensive income	$ 331.9	$ 344.7	$ 548.4