Allowance for Credit Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Accounts Receivable, Allowance for Credit Loss	$ 2.7		$ 2.4
Cumulative Effect of New Accounting Principle in Period of Adoption	0.1
Accounts Receivable, Credit Loss Expense (Reversal)	0.7	$ 0.1
Allowance for credit losses on crude oil and natural gas sales [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Accounts Receivable, Allowance for Credit Loss	0.1
Allowance for credit losses on joint interest receivables [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Accounts Receivable, Allowance for Credit Loss	$ 2.7		$ 2.4