Other Comprehensive Income and Accumulated Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated comprehensive income (loss), Beginning balance	$ (9.7)	$ (34.4)	$ 60.5
Other Comprehensive Income before Reclassifications	(18.5)	34.0	(79.5)
Amounts reclassified from other comprehensive income	(38.6)	(9.3)	(15.4)
Other comprehensive income (loss), net of tax	(57.1)	24.7	(94.9)
Accumulated comprehensive income (loss), Ending balance	(66.8)	(9.7)	(34.4)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated comprehensive income (loss), Beginning balance	(2.6)	(4.8)	(6.7)
Other Comprehensive Income before Reclassifications	(6.6)	1.5	0.5
Amounts reclassified from other comprehensive income	0.0	0.7	1.4
Other comprehensive income (loss), net of tax	(6.6)	2.2	1.9
Accumulated comprehensive income (loss), Ending balance	(9.2)	(2.6)	(4.8)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated comprehensive income (loss), Beginning balance	(0.3)	0.2	(0.4)
Other Comprehensive Income before Reclassifications	0.2	0.1	(0.2)
Amounts reclassified from other comprehensive income	0.0	(0.6)	0.8
Other comprehensive income (loss), net of tax	0.2	(0.5)	0.6
Accumulated comprehensive income (loss), Ending balance	(0.1)	(0.3)	0.2
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated comprehensive income (loss), Beginning balance	9.6	(13.9)	91.9
Other Comprehensive Income before Reclassifications	(11.1)	32.9	(88.2)
Amounts reclassified from other comprehensive income	(38.6)	(9.4)	(17.6)
Other comprehensive income (loss), net of tax	(49.7)	23.5	(105.8)
Accumulated comprehensive income (loss), Ending balance	(40.1)	9.6	(13.9)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated comprehensive income (loss), Beginning balance	(16.4)	(15.9)	(24.3)
Other Comprehensive Income before Reclassifications	(1.0)	(0.5)	8.4
Amounts reclassified from other comprehensive income	0.0	0.0	0.0
Other comprehensive income (loss), net of tax	(1.0)	(0.5)	8.4
Accumulated comprehensive income (loss), Ending balance	$ (17.4)	$ (16.4)	$ (15.9)