XML 67 R55.htm IDEA: XBRL DOCUMENT v3.23.1

Summary of Significant Accounting Policies - Narrative (Detail)	3 Months Ended
	Mar. 31, 2023
Minimum
Schedule Of Significant Accounting Policies [Line Items]
Additional terms of termination option	1 year
Maximum
Schedule Of Significant Accounting Policies [Line Items]
Additional terms of termination option	10 years

X

- Definition

Lessor operating lease termination term.

+ References

No definition available.

+ Details

Name:	g_LessorOperatingLeaseTerminationTerm
Namespace Prefix:	g_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Schedule Of Significant Accounting Policies [Line Items]

+ References

No definition available.

+ Details

Name:	g_ScheduleOfSignificantAccountingPoliciesLineItems
Namespace Prefix:	g_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: