Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 61.2	$ 46.2	$ 81.6	$ 77.3
Available-for-sale debt securities:
Change in net unrealized gains, net of tax provision of ($2.7) and ($1.9) during the three and six months ended June 30, 2020, respectively, and tax provision of ($0.2) and ($0.8) for the comparable periods in 2019, respectively	8.7	2.0	5.7	3.8
Net realized gains and losses reclassified into net income, net of tax	(0.2)	0.0	0.3	0.0
Net change on available-for-sale debt securities, net of tax	8.5	2.0	6.0	3.8
Cash flow hedges:
Change in net unrealized gains and (losses), net of tax benefit (provision) of ($1.8) and $2.4 during the three and six months ended June 30, 2020, respectively, and tax benefit (provision) of $0.2 and ($1.1) for the comparable periods in 2019, respectively	16.1	(1.8)	(8.8)	0.3
Net realized losses reclassified into net income, net of tax benefit of $0.8 and $0.9 during the three and six months ended June 30, 2020, respectively, and tax provision of ($0.6) and ($0.8) for the comparable periods in 2019, respectively	6.1	0.3	7.5	1.5
Net change on cash flow hedges, net of tax	22.2	(1.5)	(1.3)	1.8
Change in foreign currency translation adjustments	5.6	(0.9)	(9.1)	1.3
Other comprehensive income (loss), net of tax	36.3	(0.4)	(4.4)	6.9
Comprehensive income	$ 97.5	$ 45.8	$ 77.2	$ 84.2