v3.26.1
N-6
Dec. 31, 2025
Prospectus:  
Document Type N-6
Entity Registrant Name C M LIFE VARIABLE LIFE SEPARATE ACCOUNT I
Entity Central Index Key 0000943863
Entity Investment Company Type N-6
Document Period End Date Dec. 31, 2025
Amendment Flag false
Item 2. Key Information [Line Items]  
Item 18. Portfolio Companies (N-6) [Text Block]
Fund Type Fund and Adviser/Sub-Adviser Current Expenses
(expenses/average assets)		 Average Annual Total Returns
(as of 12/31/2025)
1 Year 5 Year 10 Year
Small/Mid-Cap Growth

MML VIP Wellington Small Cap Growth Equity Fund (Initial Class)

Adviser: MML Investment Advisers, LLC

Sub-Adviser: Wellington Management Company LLP

 0.94%(*) 7.34% 2.67% 10.59%
Portfolio Companies [Table Text Block]
Fund Type Fund and Adviser/Sub-Adviser Current Expenses
(expenses/average assets)		 Average Annual Total Returns
(as of 12/31/2025)
1 Year 5 Year 10 Year
Small/Mid-Cap Growth

MML VIP Wellington Small Cap Growth Equity Fund (Initial Class)

Adviser: MML Investment Advisers, LLC

Sub-Adviser: Wellington Management Company LLP

 0.94%(*) 7.34% 2.67% 10.59%
MML VIP Wellington Small Cap Growth Equity Fund (Initial Class) [Member]  
Item 2. Key Information [Line Items]  
Portfolio Company Name [Text Block] MML VIP Wellington Small Cap Growth Equity Fund (Initial Class)
Portfolio Company Adviser [Text Block] MML Investment Advisers, LLC
Portfolio Company Subadviser [Text Block] Wellington Management Company LLP
Current Expenses [Percent] 0.94%
Average Annual Total Returns, 1 Year [Percent] 7.34%
Average Annual Total Returns, 5 Years [Percent] 2.67%
Average Annual Total Returns, 10 Years [Percent] 10.59%