Related Party Transactions - Schedule of Estimated Payments Under Tax Receivable Agreement (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Related Party Transactions [Abstract]
Remainder of 2021	$ 0
2022	432
2023	746
2024	757
2025	775
Thereafter	11,398
Total Payments	$ 14,108	$ 0

Amount due pursuant to tax receivable agreement.

No definition available.

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Period Type:	instant

- Definition

Amount of estimated payments pursuant to the tax receivable agreement due after fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- Definition

Amount of estimated payments pursuant to the tax receivable agreement to be paid in remainder of current fiscal year.

+ References

No definition available.

+ Details

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Namespace Prefix:	pwp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of estimated payments pursuant to the tax receivable agreement to be paid in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

Name:	pwp_EstimatedPaymentsUnderTaxReceivableAgreementYearFour
Namespace Prefix:	pwp_
Data Type:	xbrli:monetaryItemType
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- Definition

Amount of estimated payments pursuant to the tax receivable agreement to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

Name:	pwp_EstimatedPaymentsUnderTaxReceivableAgreementYearOne
Namespace Prefix:	pwp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of estimated payments pursuant to the tax receivable agreement to be paid in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

Name:	pwp_EstimatedPaymentsUnderTaxReceivableAgreementYearThree
Namespace Prefix:	pwp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of estimated payments pursuant to the tax receivable agreement to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

Name:	pwp_EstimatedPaymentsUnderTaxReceivableAgreementYearTwo
Namespace Prefix:	pwp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

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