Commitments - Long-term Purchase Commitments (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Long-term Purchase Commitment [Line Items]
Long-term purchase commitments	$ 221.2
2020
Long-term Purchase Commitment [Line Items]
Long-term purchase commitments	57.8
2021
Long-term Purchase Commitment [Line Items]
Long-term purchase commitments	30.0
2022
Long-term Purchase Commitment [Line Items]
Long-term purchase commitments	19.5
2023
Long-term Purchase Commitment [Line Items]
Long-term purchase commitments	18.3
2024
Long-term Purchase Commitment [Line Items]
Long-term purchase commitments	18.5
Thereafter
Long-term Purchase Commitment [Line Items]
Long-term purchase commitments	$ 77.1