Equity - Accumulated Other Comprehensive Income, Net of Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications	$ 67.8	$ (5.4)	$ (18.2)
Amount reclassified from accumulated other comprehensive income (loss)	6.3	5.1	(0.3)
Other comprehensive income (loss), net	74.1	(0.3)	(18.5)
Reclassification of tax effects upon adoption of ASU 2018-02 ("Topic 220"), net			0.0
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income, Net of Tax [Roll Forward]
Balance at beginning of period	(18.5)	(18.2)	(5.4)
Reclassification of tax effects upon adoption of ASU 2018-02 ("Topic 220"), net			5.7
Balance at end of period	55.6	(18.5)	(18.2)
Unrealized Gains on Available-for- Sale Securities
Accumulated Other Comprehensive Income, Net of Tax [Roll Forward]
Balance at beginning of period	29.7	25.5	19.0
Other comprehensive income (loss) before reclassifications	5.7	4.6	0.6
Amount reclassified from accumulated other comprehensive income (loss)	(1.3)	(0.4)	0.9
Other comprehensive income (loss), net	4.4	4.2	1.5
Reclassification of tax effects upon adoption of ASU 2018-02 ("Topic 220"), net			5.0
Balance at end of period	34.1	29.7	25.5
Unrealized Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income, Net of Tax [Roll Forward]
Balance at beginning of period	(4.3)	(0.9)	6.0
Other comprehensive income (loss) before reclassifications	54.4	(8.9)	(6.4)
Amount reclassified from accumulated other comprehensive income (loss)	7.6	5.5	(1.2)
Other comprehensive income (loss), net	62.0	(3.4)	(7.6)
Reclassification of tax effects upon adoption of ASU 2018-02 ("Topic 220"), net			0.7
Balance at end of period	57.7	(4.3)	(0.9)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income, Net of Tax [Roll Forward]
Balance at beginning of period	(43.9)	(42.8)	(30.4)
Other comprehensive income (loss) before reclassifications	7.7	(1.1)	(12.4)
Amount reclassified from accumulated other comprehensive income (loss)	0.0	0.0	0.0
Other comprehensive income (loss), net	7.7	(1.1)	(12.4)
Reclassification of tax effects upon adoption of ASU 2018-02 ("Topic 220"), net			0.0
Balance at end of period	$ (36.2)	$ (43.9)	$ (42.8)