v3.20.4
Post-Employment Benefits - Additional Information (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
May 08, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Accumulated benefit obligation $ 10,500 $ 7,600    
Ultimate per capita trend rate for health care costs from 2064 and thereafter (as a percent) 4.50%      
Ultimate per capita trend rate for health care costs from 2064 and thereafter (as a percent) 4.50%      
Defined benefit plans        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Projected benefit obligation $ 11,792 8,646 $ 6,618  
Actuarial loss $ 1,105 1,703    
Defined benefit plans | Allergan plc        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Defined Benefit Plan Liabilities (Assets)       $ 156
Defined benefit plans | Equity securities        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Target investment allocations for Pension Plan (as a percent) 50.00%      
Defined benefit plans | Fixed income securities        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Target investment allocations for Pension Plan (as a percent) 20.00%      
Defined benefit plans | Asset allocation strategies and other holdings        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Target investment allocations for Pension Plan (as a percent) 30.00%      
Other post-employment plans        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Projected benefit obligation $ 795 1,050 561  
Actuarial loss $ 40 451    
Pre Sixty Five Years of Age        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Annual rate of increase in the per capita cost of covered health care obligation benefits assumed in the current year (as a percent) 6.30%      
Annual rate of increase in the per capita cost of covered health care cost benefits assumed in the current year (as a percent) 6.40%      
Post Sixty Five Years of Age        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Annual rate of increase in the per capita cost of covered health care obligation benefits assumed in the current year (as a percent) 6.70%      
Annual rate of increase in the per capita cost of covered health care cost benefits assumed in the current year (as a percent) 7.00%      
AbbVie Savings Plan        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Defined contribution plan expenses recorded $ 191 102 $ 89  
Foreign Plan [Member]        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Projected benefit obligation $ 3,500 $ 2,300