Property and Equipment - Impairment of Oil and Gas Properties (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Producing property impairments	$ 0	$ 0	$ 30
Non-producing property impairments	0	3	283
Total crude oil and natural gas impairments	$ 0	$ 3	$ 313

Costs related to the impairment of oil and gas properties.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-10.(c)(3)(ii)(A)(1))
-URI http://asc.fasb.org/extlink&oid=82851474&loc=d3e511914-122862

Name:	us-gaap_ResultsOfOperationsImpairmentOfOilAndGasProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration