| Pay vs Performance Disclosure - USD ($) | 12 Months Ended |
| Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 |
| Pay vs Performance Disclosure [Table] | | | |
| Pay vs Performance [Table Text Block] | Pay versus Performance As required by Item 402(v) of Regulation S-K, we are providing the following disclosure regarding executive compensation paid to our PEO and our non-PEO (the "Other NEOs"), and company performance for the fiscal years listed below. Our Compensation Committee did not consider the pay versus performance disclosure below in making its pay decisions for any of the years shown. For further information concerning our pay-for-performance philosophy and how we structure our executive compensation to drive and reward performance, refer to “Executive Compensation—Compensation Discussion and Analysis,” or CD&A. The amounts shown below are calculated in accordance with Item 402(v) of Regulation S-K. Value of Initial Fixed $100 Investment Based On: Year Summary Compensation on Table Total for PEO $ (1) Compensation Actually Paid to PEO $ (1)(4)(5) Average Summary Compensation Table Total for Other NEOs $ (2) Average Compensation Actually Paid to Other NEO NEOs $ (2)(4)(5) Total Shareholder Return $ (6) Peer Group Shareholder Return $ (6) Net Income (in millions) $ (7) Company Selected Measure: Revenue (8) (in millions) $ 2022 15,435,652 5,735,702 4,440,975 3,929,405 207.08 97.35 341.2 2,964.9 2021 11,985,324 36,052,076 4,962,060 6,403,115 245.47 144.19 216.9 2,422.5 (9) 2020 13,804,156 45,122,463 5,707,750 10,335,589 (3) 169.02 139.52 549.7 1,926.7 (10) (1) Kevin Sayer was our principal executive officer ("PEO") for fiscal years 2022, 2021 and 2020. (2) Non-PEO NEOs include: 2022: Jereme Sylvain, Michael Brown, Girish Naganathan, and Jake Leach; 2021: Jereme Sylvain, Paul Flynn, Jake Leach, Chad Patterson, and Quentin Blackford. 2020: Quentin Blackford, Rick Doubleday, Jake Leach, and Jeff Moy. (3) Mr. Moy and Mr. Doubleday received acceleration of time-based vesting for outstanding equity awards pursuant to Mr. Moy's retention incentive agreement dated April 2020 and Mr. Doubleday's transition and consulting agreement dated December 2020. The modifications of the RSUs are reflected above as of the modification date of April 28, 2020 for Mr. Moy and December 10, 2020 for Mr. Doubleday. | | |
| Named Executive Officers, Footnote [Text Block] | Kevin Sayer was our principal executive officer ("PEO") for fiscal years 2022, 2021 and 2020. (2) Non-PEO NEOs include: 2022: Jereme Sylvain, Michael Brown, Girish Naganathan, and Jake Leach; 2021: Jereme Sylvain, Paul Flynn, Jake Leach, Chad Patterson, and Quentin Blackford. 2020: Quentin Blackford, Rick Doubleday, Jake Leach, and Jeff Moy. | | |
| PEO Total Compensation Amount | $ 15,435,652 | $ 11,985,324 | $ 13,804,156 |
| PEO Actually Paid Compensation Amount | $ 5,735,702 | 36,052,076 | 45,122,463 |
| Adjustment To PEO Compensation, Footnote [Text Block] | The 2022 Summary Compensation Table ("SCT") totals reported for the PEO and the average of the Other NEOs for each year were subject to the following adjustments per Item 402(v)(2)(iii) of Regulation S-K to calculate “compensation actually paid" or CAP: 2022 2021 2020 PEO ($) Average for Other NEOs ($) PEO Average for Other NEOs PEO Average for Other NEOs Summary Compensation Table 15,435,652 4,440,975 11,985,324 4,962,060 13,804,156 5,707,750 Adjustments for Grant Date Fair Value Deductions for equity awards reported in Summary Compensation Table (13,212,746) (3,645,804) (9,596,745) (4,226,911) (11,178,402) (4,571,063) Adjustments for Changes in Equity Fair Value Year-end Fair Value of Equity Awards Granted During the Year that Remained Unvested as of the End of the Covered Year 16,604,680 4,062,727 18,675,363 4,851,628 17,319,529 2,262,224 Vesting Date Fair Value for Awards Granted and Vested in the Same Fiscal Year — — — — — 1,243,032 Change in Year-end Fair Value of Equity Awards Granted During Prior Years that Remained Unvested as of the End of the Covered Year (8,396,349) (545,143) 12,719,753 804,410 19,056,630 1,650,702 Change in Fair Value from Prior Year-end to Vesting Date for Awards Granted in Prior Years that Vested in Covered Fiscal Year (4,695,535) (383,349) 2,268,381 866,425 6,120,550 4,042,944 Prior Year-End Fair Value for Awards Granted in Prior Years that are forfeited during the Covered Year — — — (854,497) — — Compensation Actually Paid 5,735,702 3,929,405 36,052,076 6,403,115 45,122,463 10,335,589 (5) The SCT totals reported for the PEO and the average of the Other NEOs for each year were subject to the adjustments as required by Regulation S-K Item 402(v) (2)(iii) to calculate “compensation actually paid. Equity values are calculated in accordance with ASC Topic 718, and the valuation assumptions used to calculate fair values did not materially differ from those disclosed at the time of the grant. (6) $100 invested on December 31, 2019 in Dexcom stock or the NASDAQ Medical Equipment index, including reinvestment of any dividends. (7) We adopted ASU 2020-06 as of January 1, 2020 on a full retrospective basis and have reflected the adoption in the table above. (8) We have identified 2022 Adjusted Revenue as described in the CD&A, as the most important financial performance measure used to link compensation actually paid to the PEO and Other NEOs for 2022 to the Company’s performance. We may determine a different financial performance measure to be the most important financial performance measure in future years. (9) For a description of 2021 revenue, please refer to our 2022 Proxy Statement. | | |
| Non-PEO NEO Average Total Compensation Amount | $ 4,440,975 | 4,962,060 | 5,707,750 |
| Non-PEO NEO Average Compensation Actually Paid Amount | $ 3,929,405 | 6,403,115 | 10,335,589 |
| Compensation Actually Paid vs. Total Shareholder Return [Text Block] | Total compensation for the PEO and Other NEOs, as disclosed in the Summary Compensation Table, is comprised of salaries, annual cash incentives, and equity awards. The CAP calculation for each year includes changes in fair market value adjustments on vesting and outstanding equity awards during the year. The CAP adjustment fluctuates due to changes in the Company's stock price in each of the years. The following graph shows the relationship between the CAP to our PEO, average CAP to other NEOs, and Dexcom's cumulative total shareholder return, or TSR, and the peer group's cumulative TSR (NASDAQ Medical Equipment Index) for the fiscal years ended December 31, 2022, 2021 and 2020. | | |
| Compensation Actually Paid vs. Net Income [Text Block] | The following graph shows the relationship between the CAP to our PEO, the average CAP to other NEOs, and the Company's net income for the fiscal years ended December 31, 2022, 2021 and 2020. | | |
| Compensation Actually Paid vs. Company Selected Measure [Text Block] | The following graph shows the relationship between the CAP to our PEO, the average CAP to other NEOs, and the Company's Revenue for the fiscal years ended December 31, 2022, 2021 and 2020. | | |
| Tabular List [Table Text Block] | Tabular List of Financial Performance Measures Dexcom considers the following to be the most important financial performance measures it used to link compensation actually paid to its NEOs, for 2022, to Company performance: 2022 Adjusted Revenue Non-GAAP Operating Margin Relative Total Shareholder Return | | |
| Total Shareholder Return Amount | $ 207.08 | 245.47 | 169.02 |
| Peer Group Total Shareholder Return Amount | 97.35 | 144.19 | 139.52 |
| Net Income (Loss) | $ 341,200,000 | $ 216,900,000 | $ 549,700,000 |
| Company Selected Measure Amount | 2,964,900,000 | 2,422,500,000 | 1,926,700,000 |
| PEO Name | Kevin Sayer | | |
| Measure [Axis]: 1 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | 2022 Adjusted Revenue | | |
| Measure [Axis]: 2 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Non-GAAP Operating Margin | | |
| Measure [Axis]: 3 | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Measure Name | Relative Total Shareholder Return | | |
| PEO [Member] | Deductions for amounts reported under the “Stock Awards” column in the Summary Compensation Table [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | $ (13,212,746) | $ (9,596,745) | $ (11,178,402) |
| PEO [Member] | Year-end Fair Value of Equity Awards Granted During the Year that Remained Unvested as of the End of the Covered Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 16,604,680 | 18,675,363 | 17,319,529 |
| PEO [Member] | Vesting Date Fair Value for Awards Granted and Vested in the Same Fiscal Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| PEO [Member] | Change in Year-end Fair Value of Equity Awards Granted During Prior Years that Remained Unvested as of the End of the Covered Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (8,396,349) | 12,719,753 | 19,056,630 |
| PEO [Member] | Change in Fair Value from Prior Year-end to Vesting Date for Awards Granted in Prior Years that Vested in Covered Fiscal Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (4,695,535) | 2,268,381 | 6,120,550 |
| PEO [Member] | Prior Year-End Fair Value for Awards Granted in Prior Years that are forfeited during the Covered Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| Non-PEO NEO [Member] | Deductions for amounts reported under the “Stock Awards” column in the Summary Compensation Table [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (3,645,804) | (4,226,911) | (4,571,063) |
| Non-PEO NEO [Member] | Year-end Fair Value of Equity Awards Granted During the Year that Remained Unvested as of the End of the Covered Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 4,062,727 | 4,851,628 | 2,262,224 |
| Non-PEO NEO [Member] | Vesting Date Fair Value for Awards Granted and Vested in the Same Fiscal Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | 0 | 0 | 1,243,032 |
| Non-PEO NEO [Member] | Change in Year-end Fair Value of Equity Awards Granted During Prior Years that Remained Unvested as of the End of the Covered Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (545,143) | 804,410 | 1,650,702 |
| Non-PEO NEO [Member] | Change in Fair Value from Prior Year-end to Vesting Date for Awards Granted in Prior Years that Vested in Covered Fiscal Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | (383,349) | 866,425 | 4,042,944 |
| Non-PEO NEO [Member] | Prior Year-End Fair Value for Awards Granted in Prior Years that are forfeited during the Covered Year [Member] | | | |
| Pay vs Performance Disclosure [Table] | | | |
| Adjustment to Compensation Amount | $ 0 | $ (854,497) | $ 0 |
