Summary of Significant Accounting Policies - Narrative (Details) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Jul. 31, 2019	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Other comprehensive loss		$ 0		$ 0	$ 0
Short-term investments		150,000,000	$ 150,000,000	0
Restricted cash		1,270,000	1,270,000	179,000	280,000
Allowance for doubtful accounts		1,245,000	1,245,000	575,000	51,000		$ 92,000
Goodwill impairment			0	0
Capitalized computer software			5,600,000	4,000,000.0	1,600,000
Capitalized computer software amortization			2,500,000	900,000	200,000
Advance payments from partner			9,500,000	6,700,000
Advertising expense			4,000,000.0	5,000,000.0	$ 3,000,000.0
Cumulative effect adjustment from adoption of ASC 606						$ 4,685,000
Deferred costs and other, current		16,051,000	16,051,000	6,022,000
Deferred costs and other, noncurrent		5,700,000	5,700,000	2,447,000
Accrued expenses and other current liabilities		(27,801,000)	$ (27,801,000)	$ (16,152,000)
Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life			2 years
Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life			3 years
IPO
Property, Plant and Equipment [Line Items]
Offering expenses	$ 2,400,000
Livongo for Behavioral Health By myStrength Solution
Property, Plant and Equipment [Line Items]
Description of payment terms			In most agreements associated with our Livongo for Behavioral Health by myStrength solution, clients either pay a fixed upfront fee or a monthly fee based on the number of members to whom the solution is available. The contract term is generally one to three years, with one year auto-renewal terms.
Blood Glucose Meter and Supplies
Property, Plant and Equipment [Line Items]
Description of payment terms			In most agreements associated with our Livongo for Diabetes, Livongo for Hypertension, and Livongo for Prediabetes and Weight Management solutions, clients primarily pay monthly subscription fees based on a per participant per month model, based on the number of active enrolled members each month. In addition, clients can choose to pay an upfront amount with a lower per participant per month fee. We have determined that access to our solution is a single continuous service comprised of a series of distinct services that are substantially the same and have the same pattern of transfer (i.e. distinct days of service). These services are consumed as they are received and we recognize revenue each month using the variable consideration allocation exception. We apply this exception because we concluded that the nature of our obligations and the variability of the payment being based on the number of active members are aligned.
Accumulated Deficit
Property, Plant and Equipment [Line Items]
Cumulative effect adjustment from adoption of ASC 606						4,685,000
ASC 606 | Impact of Adoption
Property, Plant and Equipment [Line Items]
Deferred costs and other, current		1,306,000	$ 1,306,000			3,700,000
Deferred costs and other, noncurrent		1,867,000	1,867,000			800,000
Accrued expenses and other current liabilities		$ 1,011,000	$ 1,011,000			$ 200,000