Convertible Senior Notes - Outstanding Convertible Senior Notes - Summary (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Oct. 31, 2020	May 19, 2020	May 08, 2018	Jun. 27, 2017
2027 Notes
Convertible Senior Notes
Principal	$ 1,000,000		$ 1,000,000		$ 1,000,000
Less: Debt discount, net	(278,857)		(287,916)
Net carrying amount	721,143		712,084
Interest Expense
Contractual interest expense	3,125
Amortization of debt discount	9,059
Total	$ 12,184
Effective interest rate of the liability component (as a percent)	3.40%
2025 Notes
Convertible Senior Notes
Principal	$ 220,128		276,788			$ 287,500
Less: Debt discount, net	(49,672)		(65,923)
Net carrying amount	170,456		210,865
Interest Expense
Contractual interest expense	814	$ 988
Amortization of debt discount	2,719	3,076
Total	$ 3,533	$ 4,064
Effective interest rate of the liability component (as a percent)	7.90%	7.90%
Livongo Notes
Convertible Senior Notes
Principal	$ 550,000		550,000	$ 550,000
Less: Debt discount, net	(88,623)		(93,357)
Net carrying amount	461,377		456,643
Interest Expense
Contractual interest expense	1,203
Amortization of debt discount	4,734
Total	$ 5,937
Effective interest rate of the liability component (as a percent)	5.20%
2022 Notes
Convertible Senior Notes
Principal			46,762				$ 275,000
Less: Debt discount, net			(4,202)
Net carrying amount			$ 42,560
Interest Expense
Contractual interest expense	$ 104	$ 2,062
Amortization of debt discount	316	3,761
Total	$ 420	$ 5,823
Effective interest rate of the liability component (as a percent)	9.60%	10.00%