Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	6 Months Ended	9 Months Ended
	Jun. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Property, Plant and Equipment [Line Items]
Future discounted net cash flows discounted		10.00%
Capitalized costs of unproved properties included in amortization, cumulative		$ 50,000
Goodwill, Impairment Loss		62,800
Goodwill, Impairment Loss, Net of Tax		59,700
Oil and Natural Gas [Member]
Property, Plant and Equipment [Line Items]
Impairment of Oil and Gas Properties	$ 0	169,300	$ 0
Non-cash Ceiling Test Write-Down Net of Tax		127,900
Drilling [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use		$ 0