Summary of Significant Accounting Policies - Narrative (Details) - USD ($)		3 Months Ended		9 Months Ended
	Sep. 30, 2019	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2019	Jan. 01, 2020	Dec. 31, 2019
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales and marketing		$ 27,655,000	$ 14,643,000
Other comprehensive loss		0	$ 0
Operating lease right-of-use assets		17,189,000
Total operating lease liabilities		$ 18,353,000
Deferred rent						$ 500,000
Adjustment for Capitalization and Amortization of Sales Commissions
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales and marketing				$ (1,200,000)
Increase in Selling and Marketing Expense
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales and marketing				400,000
Livongo for Hypertension and Livongo for Prediabetes and Weight Management | Adjustment for Capitalization and Amortization of Device Costs
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Capitalized device costs	$ 1,900,000			$ 1,900,000
Amortization	$ 1,900,000
Accounting Standards Update 2016-02
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Operating lease right-of-use assets					$ 18,100,000
Total operating lease liabilities					$ 18,600,000