Accounts Receivable and Revenues from Contracts with Customers - Concentration Risk (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020 USD ($) Customer	Mar. 31, 2019 USD ($) Customer	Dec. 31, 2018	Dec. 31, 2019 USD ($)
Revenue | Customer Concentration Risk
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of major customers | Customer	4	3
Revenues, major customers	$ 66.5	$ 69.0
Concentration risk, percentage	73.00%	66.00%
Revenue | Customer Concentration Risk | Major Customer 1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues, major customers	$ 22.6
Concentration risk, percentage	25.00%
Revenue | Customer Concentration Risk | Major Customer 2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues, major customers	$ 15.7
Concentration risk, percentage	17.00%
Revenue | Customer Concentration Risk | Major Customer 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues, major customers	$ 15.7
Concentration risk, percentage	17.00%
Revenue | Customer Concentration Risk | Major Customer 4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Revenues, major customers	$ 12.5
Concentration risk, percentage	14.00%
Accounts Receivable | Credit Concentration Risk
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, percentage	82.00%		83.00%
Accounts receivable, major customers	$ 22.0			$ 52.7