Fair Value Measurements - Summary of Carrying Amount and Fair Value (Detail) $ in Thousands	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Debt Instrument Carrying Amount	$ 1,349,489
Term Loan Credit Agreement [Member] | Senior Secured Term Loan Facility [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount	694,220
Debt Instrument Fair Value	643,021
6.125% Senior Notes - due 2023 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount	22,924
Debt Instrument Fair Value	18,397
6.625% Senior Notes - due 2026 [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount	107,254
Debt Instrument Fair Value	80,441
First Lien Party City Notes [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount	206,775
Debt Instrument Fair Value	181,445
First Lien Anagram Notes [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount	152,301
Debt Instrument Fair Value	172,862
Second Lien Anagram Notes [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount	152,032
Debt Instrument Fair Value	$ 147,471