Summary of Significant Accounting Policies (as Restated) - Summary of Loss per Basic and Diluted Share Calculation (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended										6 Months Ended		9 Months Ended			12 Months Ended
	Mar. 31, 2019	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Jun. 30, 2019	Mar. 19, 2019	Mar. 19, 2019	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Dec. 31, 2019		Dec. 31, 2020		Dec. 31, 2018
Accounting Policies [Abstract]
Net loss attributable to OneSpaWorld	$ (30,383)	$ (71,375)	$ (47,547)	$ (20,693)	$ (148,362)	$ (7,857)	$ 2,962	$ (30,374)	$ 9	$ (25,459)	$ (25,459)	$ (169,055)	$ (27,412)	$ (216,602)	$ (35,269)		$ (287,977)		$ 9,886
Weighted average shares issued and outstanding - basic	61,118	85,148	84,968	65,916	61,169	61,118	61,118		61,118						61,118,000		74,359,000
Weighted average shares issued and outstanding - diluted	61,118	85,148	84,968	65,916	61,522	61,118	75,011		72,047						61,118,000	[1]	74,359,000	[1]
Loss per share:
Basic	$ (0.50)	$ (0.84)	$ (0.56)	$ (0.31)	$ (2.43)	$ (0.13)	$ 0.05	$ (0.50)	$ 0.00			$ (2.66)	$ (0.45)	$ (3.06)	$ (0.58)		$ (3.87)
Diluted	$ (0.50)	$ (0.84)	$ (0.56)	$ (0.31)	$ (3.23)	$ (0.13)	$ 0.04	$ (0.50)	$ 0.00			$ (2.66)	$ (0.45)	$ (3.06)	$ (0.58)		$ (3.87)

[1] Potential common shares under the treasury stock method were antidilutive because the Company reported a net loss in this period. Consequently, the Company did not have any adjustments in this period between basic and diluted loss per share related to stock options, warrants, deferred shares and restricted stock.