Equity and Warrant Liabilities - Additional Information (Details)					1 Months Ended			3 Months Ended	9 Months Ended	12 Months Ended
	Jun. 12, 2020 USD ($) $ / shares shares	Apr. 30, 2020 Vote $ / shares	Mar. 24, 2020	Mar. 19, 2019 shares	Dec. 31, 2020 USD ($) Vote $ / shares shares	Nov. 30, 2019 $ / shares	Oct. 31, 2017 shares	Mar. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) Vote $ / shares shares	Dec. 07, 2020 USD ($) $ / shares	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Oct. 19, 2017 $ / shares shares
Non-voting common share convert into voting common share					1					1
Percentage of voting power on contingent conversion triggering event										44.90%
Warrant exercise price | $ / shares									$ 11.50
Proceeds from 2020 private placement, net of issuance costs paid | $										$ 68,602,000
Proceeds from the issuance of common shares | $									$ 122,510,000
Warrants and rights Outstanding | $					$ 16,150,379			$ 5,600,000	$ 16,498,900	$ 16,150,379		$ 61,300,000	$ 36,200,000	$ 46,900,000	$ 47,500,000	$ 43,900,000
Consideration Arrangements Description										As part of the equity consideration transferred in the Business Combination on March 19, 2019, Steiner and Haymaker Sponsor, LLC (“Haymaker Sponsor”) received deferred shares which provided the right to receive 5,000,000 and 1,600,000 OneSpaWorld common stock, respectively. The issuance of the OneSpaWorld common shares related to the Deferred Shares is contingent upon the earliest occurrence of any of the following events: (i) OneSpaWorld share price reaching $20 per share for five consecutive trading dates, as adjusted to reflect any stock split, reverse stock split, stock dividend, payment of dividends and other events as defined in the applicable Deferred Shares agreement, (ii) in the event of a change of control, as defined, of the Company if the price per share paid in connection with such change in control is equal to or greater than $20; however, if the price per share paid in connection with such change in control is less than $20, then no OneSpaWorld common shares will be issued and all the rights to receive the shares will be forfeited for no consideration, and (iii) ten years from the date of the Business Combination agreement
Deferred shares										5,000,000
Warrants Available For Conversion									1,100
Conversion Of Warrants Into Shares									1,100
Class Of Warrant Or Right Repurchased Shares								348,521
Payments For Repurchase Of Warrants | $								$ 900,000		$ 879,000
Warrants agreement expire date										5 years
Redemption price of warrant | $ / shares					$ 0.01					$ 0.01
Share price minimum for redemption | $ / shares					$ 18.00					$ 18.00
Cash dividend per share | $ / shares						$ 0.04
Dividend declared date			Feb. 26, 2020							Feb. 26, 2020
Dividend payable date			May 29, 2020
Dividend record date			Apr. 10, 2020
Dividends payable | $					$ 2,400,000				$ 2,400,000	$ 2,400,000
Steiner [Member]
Deferred shares				5,000,000
Haymaker Sponsor LLC [Member]
Deferred shares				1,600,000
Two Directors [Member] | Minimum [Member] | Steiner [Member]
Percentage of issued and outstanding common shares										15.00%
One Directors [Member] | Minimum [Member] | Steiner [Member]
Percentage of issued and outstanding common shares										5.00%
2020 Private Placement [Member]
Common stock and warrants sold | $	$ 75,000,000
Weighted average price | $ / shares										$ 10.50
2020 Private Placement [Member] | Haymaker Sponsor LLC [Member]
Warrants issued to purchase shares							8,000,000
At-the- Market Equity Offering [Member] | Common Stock [Member]
Common shares, par value | $ / shares											$ 0.0001
Common stock, shares sold					1,259,195					1,259,195
Proceeds from the issuance of common shares | $					$ 11,100,000					$ 11,100,000
Remaining available under sales agreement | $					38,000,000					$ 38,000,000
At-the- Market Equity Offering [Member] | Common Stock [Member] | Maximum [Member]
Aggregate offering amount | $											$ 50,000,000
2019 PIPE Warrants [Member]
Warrant exercise price | $ / shares																	$ 11.50
Warrants to purchase common stock																	8,000,000
Warrants transferred to investors																	3,105,294
Investment Agreement | 2020 PIPE Warrants [Member]
Number of common stock voting rights | Vote		1
Warrant exercise price | $ / shares		$ 5.75
Common shares, par value | $ / shares		14.50
Price per warrants | $ / shares		$ 0.01
Warrant expiration, description										will expire on the earlier of (i) the fifth anniversary of the closing of the 2020 Private Placement or (ii) the Redemption Date (as defined below). Each Warrant entitles the holder to purchase one share of OneSpaWorld common stock at an exercise price of $5.75. The 2020 PIPE Warrants may be exercised on a “cashless” basis, in accordance with a specified formula. In addition, the Company may, at any time prior to their expiration, elect to redeem not less than all of such then-outstanding 2020 PIPE Warrants at a price of $0.01 per warrant, provided that the last sales price of the common shares reported has been at least $14.50 per share (subject to adjustment in accordance with certain specified events), on each of twenty trading days within the thirty-trading day period ending on the third business day prior to the date on which notice of the redemption is given (the “Redemption Date”)
Warrants and rights Outstanding | $					$ 5,000,000					$ 5,000,000
Investment Agreement | Steiner Leisure Limited [Member] | 2020 Private Placement [Member]
Common stock and warrants sold | $	75,000,000
Common stock and warrants sold offering expenses | $	6,400,000
Proceeds from 2020 private placement, net of issuance costs paid | $	68,600,000
Investment Agreement | Steiner Leisure Limited [Member] | 2020 Private Placement [Member] | 2020 PIPE Warrants [Member]
Common stock and warrants sold offering expenses | $	$ 1,400,000
Common Class A [Member]
Common stock, shares authorized					250,000,000					250,000,000
Common stock, par value | $ / shares					$ 0.0001					$ 0.0001
Number of common stock voting rights | Vote					1					1
Common stock, shares issued									61,119,398
Common stock, shares outstanding									61,119,398
Voting Common Stock [Member]
Common stock, shares authorized					225,000,000				225,000,000	225,000,000
Common stock, par value | $ / shares					$ 0.0001				$ 0.0001	$ 0.0001
Common stock, shares issued					69,292,596				61,119,398	69,292,596
Common stock, shares outstanding					69,292,596				61,119,398	69,292,596
Deferred shares										2,800,000
Voting Common Stock [Member] | 2020 Private Placement [Member]
Number of shares issued										6,564
Voting Common Stock [Member] | At-the- Market Equity Offering [Member]
Number of shares issued										1,259
Voting Common Stock [Member] | Investment Agreement | 2020 Private Placement [Member] | Co-Investors [Member]
Number of shares issued	3,700,000
Warrants issued to purchase shares	1,000,000
Warrant exercise price | $ / shares	$ 5.75
Non-Voting Common Stock [Member]
Common stock, shares authorized					25,000,000				25,000,000	25,000,000
Common stock, par value | $ / shares					$ 0.0001				$ 0.0001	$ 0.0001
Common stock, shares issued					17,185,500				0	17,185,500
Common stock, shares outstanding					17,185,500				0	17,185,500
Deferred shares										2,200,000
Non-Voting Common Stock [Member] | 2020 Private Placement [Member]
Number of shares issued										17,186
Non-Voting Common Stock [Member] | Investment Agreement | Steiner Leisure Limited [Member] | 2020 Private Placement [Member]
Number of shares issued	15,000,000
Warrants issued to purchase shares	4,000,000
Warrant exercise price | $ / shares	$ 5.75