Equity - Additional Information (Details)						9 Months Ended		12 Months Ended
	Mar. 16, 2020 USD ($) $ / shares shares	Jan. 09, 2020 USD ($) $ / shares shares	Nov. 04, 2019 USD ($) $ / shares shares	May 31, 2019 USD ($) $ / shares shares	Feb. 15, 2019 USD ($) $ / shares shares	Sep. 30, 2021 USD ($) $ / shares shares	Sep. 30, 2020 USD ($)	Dec. 31, 2020 $ / shares shares		Jul. 16, 2021 $ / shares		Nov. 01, 2019 $ / shares shares	May 29, 2019 $ / shares shares	May 07, 2018 $ / shares shares
Stockholders Equity Details [Line Items]
Common stock, shares authorized						730,000,000		155,640,290
Common stock, par value (in Dollars per share) | $ / shares						$ 0.0001		$ 0.0001		$ 0.0001
Common stock, voting Rights						common stock are entitled to one vote per share
Treasury stock, Shares						0		90,834
Preferred stock, shares authorized						10,000,000		0
Preferred stock, shares issued						0		0
Preferred stock, shares outstanding						0		0
Preferred stock, voting rights						Preferred Stock were entitled to vote
Dividend accrued on preferred stock, percentage						6.00%
Cash dividends declared or paid | $						$ 0
Preferred stock dividend payment description						The holders of Preferred Stock were entitled to receive noncumulative dividends when, as and if declared by the board of directors. Dividends accrued on the Preferred Stock at a rate of 6% of the Original Issue Price per year; however, such dividends were only payable when, as and if declared by the board of directors. Holders of the Preferred Stock were to be paid dividends prior and in preference to any dividends on common stock. As of the Closing Date, no cash dividends were declared or paid.
(Income) expense related to warrant liabilities | $						$ (2,258,000)	$ 52,065,000
Warrants outstanding						42,686,195
Legacy GX Warrants
Stockholders Equity Details [Line Items]
Description of exercisable terms						The Public Warrants became exercisable on August 15, 2021, which is the later of (a) 30 days after the consummation of a Business Combination or (b) 12 months from the effective date of the registration statement relating to GX’s initial public offering.
Warrants
Stockholders Equity Details [Line Items]
Warrants exercisable period after consummation of business combination						30 days
Warrants exercisable period from effective date of registration statement of initial public offering						12 months
Public warrants exercisable for cash						0
Warrant term						5 years
Call price of public warrants | $ / shares						$ 0.01
Minimum prior written notice period for redemption						30 days
Description of call provision						• at any time while the Public Warrants are exercisable,   • upon not less than 30 days’ prior written notice of redemption to each Public Warrant holder,   • if, and only if, there is a current registration statement in effect with respect to the issuance of the common stock underlying such warrants at the time of redemption and for the entire 30-day trading period referred to above and continuing
Sponsors [Member]
Stockholders Equity Details [Line Items]
Aggregate number of warrants issued to sponsor as repayment for working capital loans						1,499,999
Legacy Celularity
Stockholders Equity Details [Line Items]
Common stock, shares authorized								155,640,290
Common stock, par value (in Dollars per share) | $ / shares								$ 0.0001
Common stock, voting Rights								common stock entitled the holder to one vote
Treasury stock, Shares								90,834
Conversion of preferred stock, description						The conversion ratio of each series of Preferred Stock was determined by dividing the Original Issue Price of each series by the Conversion Price of each series. The Original Issue Price per share was $6.27 for Series A and X Preferred Stock (the “Series A and X Original Issue Price”) and $7.53 for Series B Preferred Stock (the “Series B Original Issue Price”), each subject to appropriate adjustment in the event of any stock dividend, stock split, combination or other similar recapitalization and other adjustments as set forth in Legacy Celularity’s certificate of incorporation, as amended and restated. As of December 31, 2020, the Conversion Price was equal to the Original Issue Price for each series of Preferred Stock. Accordingly, as of December 31, 2020, each share of each series of Preferred Stock was convertible into shares of Legacy Celularity common stock on a one-for-one basis.
Conversion ratio of preferred stock								1
Legacy Celularity | Warrants | Series B Preferred Stock Purchase Agreement [Member]
Stockholders Equity Details [Line Items]
Proceeds from the issuance of equity and warrants | $	$ 17,954,000
Minimum | Legacy Celularity | Preferred Stock
Stockholders Equity Details [Line Items]
Percentage of shares required for voting						50.00%
Gross proceeds | $						$ 50,000,000
Conversion price per share of common stock | $ / shares						$ 9.41
Class A Common Stock
Stockholders Equity Details [Line Items]
Common stock, shares authorized						730,000,000
Common stock, par value (in Dollars per share) | $ / shares						$ 0.0001				0.0001
Warrants outstanding						42,686,195
Redeemable Convertible Preferred Stock
Stockholders Equity Details [Line Items]
Temporary equity, shares undesignated								0
Redeemable Convertible Preferred Stock | Legacy Celularity
Stockholders Equity Details [Line Items]
Warrants to purchase redeemable convertible preferred stock, shares authorized								116,526,341
Redeemable convertible preferred stock, par value (in Dollars per share) | $ / shares								$ 0.0001
Series B Redeemable Convertible Preferred Stock
Stockholders Equity Details [Line Items]
Warrants to purchase redeemable convertible preferred stock, shares authorized						0		75,088,327
Redeemable convertible preferred stock, par value (in Dollars per share) | $ / shares						$ 0.0001		$ 0.0001
Redeemable convertible preferred stock, shares issued						0		41,205,482
Series B Redeemable Convertible Preferred Stock | Legacy Celularity
Stockholders Equity Details [Line Items]
Purchase price | $ / shares						$ 7.53
Series B Redeemable Convertible Preferred Stock | Legacy Celularity | Dragasac Warrant
Stockholders Equity Details [Line Items]
Warrants outstanding to purchase shares of common stock			6,529,818	3,431,223	6,640,695									16,601,736
Exercise price of warrant | $ / shares			$ 6.77	$ 7.29	$ 7.53									$ 7.53
Gross proceeds from warrants exercised | $			$ 44,178,000	$ 25,000,000	$ 50,000,000
Series B Redeemable Convertible Preferred Stock | Legacy Celularity | Amended and Restated Dragasac Warrant
Stockholders Equity Details [Line Items]
Warrants outstanding to purchase shares of common stock													3,431,223
Exercise price of warrant | $ / shares													$ 7.29
Series B Redeemable Convertible Preferred Stock | Legacy Celularity | Amended Dragasac Warrant
Stockholders Equity Details [Line Items]
Warrants outstanding to purchase shares of common stock												6,529,818
Exercise price of warrant | $ / shares												$ 6.77
Series B Redeemable Convertible Preferred Stock | Legacy Celularity | Series B Preferred Stock Purchase Agreement [Member]
Stockholders Equity Details [Line Items]
Warrants to purchase redeemable convertible preferred stock, shares authorized	13,281,386
Redeemable convertible preferred stock, shares issued	13,620,063
Proceeds from the issuance of equity and warrants | $	$ 84,596,000
Series B Redeemable Convertible Preferred Stock | Legacy Celularity | Warrants | Series B Preferred Stock Purchase Agreement [Member]
Stockholders Equity Details [Line Items]
Proceeds from the issuance of equity and warrants | $	$ 102,550,000
Series B Preferred Stock Purchase Agreement [Member] | Minimum | Legacy Celularity
Stockholders Equity Details [Line Items]
Number of shares required to be outstanding for voting						5,000,000
Series A Redeemable Convertible Preferred Stock
Stockholders Equity Details [Line Items]
Warrants to purchase redeemable convertible preferred stock, shares authorized						0		29,484,740
Redeemable convertible preferred stock, par value (in Dollars per share) | $ / shares						$ 0.0001		$ 0.0001
Redeemable convertible preferred stock, shares issued						0		29,484,740
Series A Redeemable Convertible Preferred Stock | Legacy Celularity
Stockholders Equity Details [Line Items]
Purchase price | $ / shares						$ 6.27
Series X Redeemable Convertible Preferred Stock
Stockholders Equity Details [Line Items]
Warrants to purchase redeemable convertible preferred stock, shares authorized						0		11,953,274
Redeemable convertible preferred stock, par value (in Dollars per share) | $ / shares						$ 0.0001		$ 0.0001
Redeemable convertible preferred stock, shares issued						0		11,953,274
Series X Redeemable Convertible Preferred Stock | Legacy Celularity
Stockholders Equity Details [Line Items]
Purchase price | $ / shares						$ 6.27
Series B Preferred Stock
Stockholders Equity Details [Line Items]
Exercise price of warrant | $ / shares						$ 7.53		$ 7.53	[1]	$ 7.53	[1]
Series B Preferred Stock | Legacy Celularity | Investors [Member]
Stockholders Equity Details [Line Items]
Exercise price of warrant | $ / shares	$ 7.53
Aggregate of shares	13,620,063
Number of warrants issued to the investors	13,281,386
Series B Preferred Stock | Legacy Celularity | Dragasac Warrant
Stockholders Equity Details [Line Items]
Exercise price of warrant | $ / shares		$ 6.77
Aggregate number of shares issued		6,529,818
Warrants per share, percentage		80.00%
(Income) expense related to warrant liabilities | $		$ 11,988
Series B Preferred Stock | Legacy Celularity | Warrants | Investors [Member]
Stockholders Equity Details [Line Items]
Proceeds from the issuance of equity and warrants | $	$ 102,550,000

[1] The warrants are exercisable at a price of $7.53 per share on the first to occur of: (a) the 60-month anniversary of the date of issuance of the warrants, (b) the consummation of an agreement for a public exit event, and (c) the consummation of a change of control