Accumulated Other Comprehensive Income (Loss) Reclassification Adjustments (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Interest expense		$ (50.9)	$ (26.0)
Investment Income, Nonoperating		2.9	3.5
Total reclassifications for the period		0.0	2.2
Interest Rate Hedges | Reclassification out of Accumulated Other Comprehensive Income [Member]
Interest expense		0.5	0.4
Net actuarial loss amortization | Reclassification out of Accumulated Other Comprehensive Income [Member]
Net periodic benefit cost	[1]	(0.5)	1.8
Net actuarial loss amortization, tax		(0.3)	(0.4)
Pension and Other Post-retirement Benefits
Total reclassifications for the period		$ (0.5)	$ 1.8

[1] Pension and other post-retirement benefits AOCI components are included in the computation of net periodic benefit cost (refer to note 16).