Net Income (Loss) Per Share Attributable to Common Stockholders - Common Stock Equivalents excluded from Calculation of Diluted Net Income (Loss) Per Share attributable to Common Stockholders (Details) - shares	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,157,431	20,327,778	21,381,913
Stock options issued and outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	145,350	1,322,176	1,722,861
Unvested restricted stock units issued and outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	773,678	18,386,271	18,755,538
Shares of Class A common stock reserved for Twilio.org
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	353,633	442,041
Shares of Class A common stock committed under ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	238,403	265,698	426,199
Shares of Class A common stock in escrow
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	0	31,503
Shares of Class A common stock in escrow subject to future vesting
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	0	0	3,771