Fair Value of Financial Instruments - Schedule of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Assets:
Derivatives	$ 6.5	$ 5.2
Liabilities:
Derivatives	8.7	5.5
Fair Value, Measurements, Recurring
Assets:
Investments	13.4	13.1
Derivatives	6.5	5.2
Total assets	19.9	18.3
Liabilities:
Derivatives	8.7	5.5
Total liabilities	8.7	5.5
Fair Value, Measurements, Recurring | Level 1
Assets:
Investments	13.4	13.1
Derivatives	0.0	0.0
Total assets	13.4	13.1
Liabilities:
Derivatives	0.0	0.0
Total liabilities	0.0	0.0
Fair Value, Measurements, Recurring | Level 2
Assets:
Investments	0.0	0.0
Derivatives	6.5	5.2
Total assets	6.5	5.2
Liabilities:
Derivatives	8.7	5.5
Total liabilities	8.7	5.5
Fair Value, Measurements, Recurring | Level 3
Assets:
Investments	0.0	0.0
Derivatives	0.0	0.0
Total assets	0.0	0.0
Liabilities:
Derivatives	0.0	0.0
Total liabilities	$ 0.0	$ 0.0