Number of Productive Crude Oil and Natural Gas Wells in which we Held an Interest (Detail)	Jun. 30, 2020 Wells
Disclosure of productive wells [line items]
Crude oil wells, Gross	473
Crude oil wells, Net	222
Natural gas wells, Gross	170
Natural gas wells, Net	58
Total, Gross	643
Total, Net	280
Australia [member]
Disclosure of productive wells [line items]
Crude oil wells, Gross	353
Crude oil wells, Net	176
Natural gas wells, Gross	162
Natural gas wells, Net	54
Total, Gross	515
Total, Net	230
United States [member]
Disclosure of productive wells [line items]
Crude oil wells, Gross	61
Crude oil wells, Net	24
Natural gas wells, Gross	0
Natural gas wells, Net	0
Total, Gross	61
Total, Net	24
Other countries [member]
Disclosure of productive wells [line items]
Crude oil wells, Gross	59
Crude oil wells, Net	22
Natural gas wells, Gross	8
Natural gas wells, Net	4
Total, Gross	67
Total, Net	26

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Productive well number of wells gross.

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Productive well number of wells net.

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Number of producing gas wells and gas wells capable of production with working interest ownership.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1208
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Number of producing gas wells and gas wells capable of production representing summation of fractional ownership working interest to whole.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1208
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Number of producing oil wells and oil wells capable of production with working interest ownership.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1208
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Number of producing oil wells and oil wells capable of production representing summation of fractional ownership working interest to whole.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1208
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