Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32621-109319

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 25
-Paragraph 20
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=117330534&loc=d3e28680-109314

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32632-109319

Name:	us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsDomestic
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating Loss Carryforwards [Line Items]
Results of Operations, Impairment of Oil and Gas Properties		$ 881.1
Deferred Tax Assets, Operating Loss Carryforwards, Domestic	$ 470.0			$ 470.0
Effective Income Tax Rate, Continuing Operations	(0.60%)		40.10%	0.50%	10.40%
Delaware Basin Assets [Member]
Operating Loss Carryforwards [Line Items]
Results of Operations, Impairment of Oil and Gas Properties				$ 882.3