Schedule I - Condensed Financial Information of Registrant - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows provided by (used in) operating activities:
Net (loss) income	$ (96,395)	$ 239,665	$ (130,059)	$ (541,668)	$ (268,829)	$ (281,745)	$ 48,005	$ (30,289)	$ (528,457)	$ (532,858)	$ 122,819
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Change in due to/from affiliates									28,002	(65,617)	12,138
Net cash provided by operating activities									77,200	43,693	101,856
Cash flows provided by (used in) financing activities:
Treasury stock purchases									(96)	(156)	(40,197)
Exercise of stock options									147	1,148	2,269
Net cash provided by (used in) financing activities									93,704	(237,710)	56,170
Cash and cash equivalents at beginning of period				$ 34,917					34,917
Cash and cash equivalents at end of period	$ 119,532				$ 34,917				119,532	34,917
Party City Holdco Inc. [Member]
Cash flows provided by (used in) operating activities:
Net (loss) income									(528,238)	(532,495)	122,850
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Equity in net income of subsidiaries									528,238	532,495	(122,850)
Change in due to/from affiliates									(49)	(989)	37,928
Net cash provided by operating activities									(49)	(989)	37,928
Cash flows provided by (used in) financing activities:
Treasury stock purchases									(97)	(156)	(40,197)
Exercise of stock options									146	1,145	2,269
Net cash provided by (used in) financing activities									$ 49	$ 989	$ (37,928)