Revenue from Contracts with Customers - Summary of Revenue from Contracts with Customers (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Total revenues	$ 561,011	$ 544,878	$ 1,068,835	$ 1,021,877
Retail Segment [Member]
Disaggregation of Revenue [Line Items]
Total revenues	414,263	403,026	780,555	745,331
Wholesale Segment [Member]
Disaggregation of Revenue [Line Items]
Total revenues	146,748	141,852	288,280	276,546
Party City Stores [Member] | Retail Segment [Member]
Disaggregation of Revenue [Line Items]
Net sales	376,222	363,872	707,067	668,886
Global E-commerce [Member] | Retail Segment [Member]
Disaggregation of Revenue [Line Items]
Net sales	35,131	35,929	67,862	70,184
Domestic [Member] | Wholesale Segment [Member]
Disaggregation of Revenue [Line Items]
Net sales	79,397	81,354	158,956	165,695
International [Member] | Wholesale Segment [Member]
Disaggregation of Revenue [Line Items]
Net sales	67,351	60,498	129,324	110,851
Net Sales [Member]
Disaggregation of Revenue [Line Items]
Net sales	558,101	541,653	1,063,209	1,015,616
Net Sales [Member] | Retail Segment [Member]
Disaggregation of Revenue [Line Items]
Net sales	411,353	399,801	774,929	739,070
Royalties and Franchise Fees [Member]
Disaggregation of Revenue [Line Items]
Net sales	2,910	3,225	5,626	6,261
Royalties and Franchise Fees [Member] | Retail Segment [Member]
Disaggregation of Revenue [Line Items]
Net sales	$ 2,910	$ 3,225	$ 5,626	$ 6,261