Stockholders' Equity Members' Deficit (Tables)

9 Months Ended

Sep. 30, 2021

Stockholders Equity Note [Abstract]

Schedule of Common Stock

The Company’s common stock/units consisted of the following common units and common stock as of the periods ended September 30, 2021 (Successor) and December 31, 2020 (Successor):

	Redeemable Class A Units			Class A-1 Units			Class A-2 Units			Class B Units			Common Stock		Total
Balance as of April 13,    2020 (Successor)		—			—			—			—			—		—
Issued		35,000			959,563			49,946			—			—		1,044,509
Balance as of    December 31, 2020		35,000			959,563			49,946			—			—		1,044,509
Issued		—			—			1,687			—			—		1,687
Vested Class B Profits    Interests		—			—			—			17,920			—		17,920
Conversion of pre-IPO    units to common stock		(35,000	)		(959,563	)		(51,633	)		(17,920	)		340,849		(723,267	)
Initial Public Offering		—			—			—			—			32,800		32,800
Endowment to the    LifeStance Health    Foundation		—			—			—			—			500		500
Balance as of September    30, 2021 (Successor)		—			—			—			—			374,149		374,149