Goodwill - Additional Information (Detail) - USD ($)	3 Months Ended					12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2019
Goodwill [Line Items]
Goodwill, impairment loss	$ 0		$ 401,436,000	$ 556,056,000	$ 556,056,000
Impairment charge on intangible asset		$ 2,423,000
Tangible asset impairment charges	$ 0	31,277,000
Trade Names [Member]
Goodwill [Line Items]
Impairment of indefinite-lived intangibles		$ 11,032,000
Party City Holdings Inc [Member]
Goodwill [Line Items]
Impairment charge on intangible asset			131,287,000			$ 0
Halloween City Trade Name [Member]
Goodwill [Line Items]
Impairment charge on intangible asset			3,925,000			$ 6,575,000
Operating Segments [Member] | Retail Segment [Member]
Goodwill [Line Items]
Goodwill, impairment loss			253,110,000	271,500,000	224,100,000
Operating Segments [Member] | Wholesale Segment [Member]
Goodwill [Line Items]
Goodwill, impairment loss			$ 148,326,000	$ 25,400,000	$ 35,000,000