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Developed and Undeveloped Acreage (Including Both Leases and Concessions) Held (Detail) a in Thousands | Jun. 30, 2018 a
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Gas and oil acreage [Line Items] |
Developed acreage, Gross | 3,464
Developed acreage, Net | 1,556
Undeveloped acreage, Gross | 8,668
Undeveloped acreage, Net | 6,027
Australia [member] |
Gas and oil acreage [Line Items] |
Developed acreage, Gross | 2,152
Developed acreage, Net | 823
Undeveloped acreage, Gross | 4,326
Undeveloped acreage, Net | 2,605
United States [member] |
Gas and oil acreage [Line Items] |
Developed acreage, Gross | 1,137
Developed acreage, Net | 669
Undeveloped acreage, Gross | 1,313
Undeveloped acreage, Net | 1,085
Other countries [member] |
Gas and oil acreage [Line Items] |
Developed acreage, Gross | 175
Developed acreage, Net | 64
Undeveloped acreage, Gross | 3,029
Undeveloped acreage, Net | 2,337

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- Definition Area spaced or assigned to productive wells in which a working interest is owned. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1208 -Paragraph (a) + Details
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- Definition Fractional interest owned based on working interests or other economic arrangements of area spaced or assigned to productive wells. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1208 -Paragraph (a) + Details
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- Definition Lease area in which a working interest is owned and on which wells have not been drilled or completed to a point that would permit the production of commercial quantities of oil and gas regardless of whether or not such area contains proved reserves. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1208 -Paragraph (b) + Details
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- Definition Fractional interest owned based on working interests or other economic arrangements of lease area on which wells have not been drilled or completed to a point that would permit the production of commercial quantities of oil and gas regardless of whether or not such area contains proved reserves. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1208 -Paragraph (b) + Details
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