Share-Based Compensation - Summary of Stock Option Activity under 2014 Plan (Detail) $ / shares in Units, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2021 USD ($) $ / shares shares	[1]	Dec. 31, 2020 USD ($) $ / shares shares	[1]
Share-based Payment Arrangement, Disclosure [Abstract]
Number of options, Outstanding at the beginning of the period | shares	20,525,332
Number of options, Granted | shares	1,013,759
Number of options, Exercised | shares	(3,302,831)
Number of options, Forfeited | shares	(248,505)
Number of options, Outstanding at the end of the period | shares	17,987,755		20,525,332
Number of options, Exercisable at the end of the period | shares	12,272,727
Weighted average exercise price, Outstanding at the beginning of the period | $ / shares	$ 0.71
Weighted average exercise price, Granted | $ / shares	7.64
Weighted average exercise price, Exercised | $ / shares	0.59
Weighted average exercise price, Forfeited | $ / shares	1.39
Weighted average exercise price, Outstanding at the end of the period | $ / shares	1.11		$ 0.71
Weighted average exercise price, Exercisable at the end of the period | $ / shares	$ 0.60
Weighted average remaining contractual term (in years)	6 years 11 months 12 days		6 years 9 months 3 days
Weighted average remaining contractual term (in years) Exercisable at the end of the period	6 years 1 month 28 days
Aggregate intrinsic value, Outstanding | $	$ 129,440		$ 153,934
Aggregate intrinsic value, Exercisable at the end of the period | $	$ 94,584

[1] Number of options and the weighted average exercise price have been adjusted to reflect the exchange of Old Talkspace’s common stock for Talkspace’s common stock at an exchange ratio of approximately 1.134140 in June 2021 as a result of the Business Combination. See Note 3, “Business Combination,” for further details.