XML 97 R81.htm IDEA: XBRL DOCUMENT v3.21.1

Shareholders' Equity - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020 Vote
Equity [Abstract]
Number of votes per share	1

X

- Definition

Number of votes per share.

+ References

No definition available.

+ Details

Name:	gigm_NumberOfVotesPerShare
Namespace Prefix:	gigm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- References

No definition available.

+ Details

Name:	us-gaap_EquityAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration