Service Providers and Related Party Agreements - Additional Information (Detail)	12 Months Ended
Dec. 31, 2019 shares
Related Party Transactions [Abstract]
Number of shares for creation and redemption from fund by authorized participants in specified quantity	50,000

Number of shares for creation and redemption from fund by authorized participants in specified quantity.

No definition available.

Name:	gcc_NumberOfSharesForCreationAndRedemptionFromFundByAuthorizedParticipantsInSpecifiedQuantity
Namespace Prefix:	gcc_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration