The amount of cumulative investment in equity method investments.

No definition available.

Name:	ctgo_EquityMethodInvestmentCumulativeInvestment
Namespace Prefix:	ctgo_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the cumulative income (loss), from inception to the balance sheet date, of an equity method investment.

+ References

No definition available.

+ Details

Name:	ctgo_EquityMethodInvestmentSummarizedFinancialInformationInceptionToDateCumulativeIncomeLoss
Namespace Prefix:	ctgo_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents entity's share of losses from equity method investment including losses that are not recognized in earnings

+ References

No definition available.

+ Details

Name:	ctgo_LossFromEquityMethodInvestmentsUnrecorded
Namespace Prefix:	ctgo_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the suspended losses incurred during the period. This may be for, example, an equity method investment.

+ References

No definition available.

+ Details

Name:	ctgo_SuspendedLosses
Namespace Prefix:	ctgo_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This element represents the aggregate cost of investments accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 25
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8813-108599

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The cash outflow associated with the investment in or advances to an entity in which the reporting entity shares control of the entity with another party or group.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3213-108585

+ Details

Name:	us-gaap_PaymentsToAcquireInterestInJointVenture
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=ctgo_TheJointVentureCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=ctgo_RoyalGoldMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 4 - Investment in the Joint Venture Company (Details Textual) - USD ($)	3 Months Ended		6 Months Ended		48 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Jun. 30, 2018	Apr. 26, 2018	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015	Jan. 08, 2015	Jun. 30, 2014
Equity Method Investments
The Joint Venture Company [Member]
Equity Method Investment, Aggregate Cost	$ 1,400,000		$ 1,400,000		$ 1,400,000						$ 1,400,000
Equity Method Investment, Ownership Percentage	60.00%		60.00%		60.00%		60.00%
Loss from Equity Method Investments, Unrecorded	$ 500,000	$ 900,000	$ 3,300,000	$ 3,000,000
Equity Method Investment, Summarized Financial Information, Inception-to-date Cumulative Income (Loss)	30,200,000		30,200,000		$ 30,200,000	27,000,000
Equity Method Investments	0		0		0	$ 0		$ 0	$ 0	$ 0		$ 0
Equity Method Investment, Cumulative Investment	$ 6,800,000		6,800,000		6,800,000
Suspended Losses					23,400,000
The Joint Venture Company [Member] \| Royal Gold [Member]
Payments to Acquire Interest in Joint Venture			$ 33,600,000		$ 33,600,000
Equity Method Investment, Ownership Percentage	40.00%		40.00%		40.00%		40.00%