v3.26.1
FAIR VALUE MEASUREMENTS (Details) - EBP 001 - USD ($)
Dec. 31, 2025
Dec. 31, 2024
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value $ 154,482,029 $ 137,734,317
Level 1    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 137,566,685 123,661,565
Level 1 | Aggressive Bonds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 4,271,005 2,373,979
Level 1 | Intermediate/Long-term Bonds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 7,887,004 7,962,781
Level 1 | Large-Cap Stocks    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 55,010,596 52,029,326
Level 1 | Small/Mid-Cap Stocks    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 20,580,235 20,793,649
Level 1 | International Stocks    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 7,136,945 6,118,710
Level 1 | Multi-Asset/Other    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 42,171,232 34,281,497
Level 1 | Personal Choice Retirement Account    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 509,668 101,623
Level 1 | InterDigital Stock Fund    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 2    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 9,746,855 6,387,369
Level 2 | Aggressive Bonds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 2 | Intermediate/Long-term Bonds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 2 | Large-Cap Stocks    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 2 | Small/Mid-Cap Stocks    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 2 | International Stocks    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 2 | Multi-Asset/Other    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 2 | Personal Choice Retirement Account    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 2 | InterDigital Stock Fund    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 9,746,855 6,387,369
Level 3    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 3 | Aggressive Bonds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 3 | Intermediate/Long-term Bonds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 3 | Large-Cap Stocks    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 3 | Small/Mid-Cap Stocks    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 3 | International Stocks    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 3 | Multi-Asset/Other    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 3 | Personal Choice Retirement Account    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Level 3 | InterDigital Stock Fund    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 0 0
Total    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 147,313,540 130,048,934
Total | Aggressive Bonds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 4,271,005 2,373,979
Total | Intermediate/Long-term Bonds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 7,887,004 7,962,781
Total | Large-Cap Stocks    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 55,010,596 52,029,326
Total | Small/Mid-Cap Stocks    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 20,580,235 20,793,649
Total | International Stocks    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 7,136,945 6,118,710
Total | Multi-Asset/Other    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 42,171,232 34,281,497
Total | Personal Choice Retirement Account    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 509,668 101,623
Total | InterDigital Stock Fund    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value 9,746,855 6,387,369
Fair Value Measured at Net Asset Value Per Share | Stable Pooled Fund    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments at fair value $ 7,168,489 $ 7,685,383