STOCKHOLDERS' EQUITY - Narrative (Details) - USD ($)
$ / shares in Units, shares in Thousands
 3 Months Ended 4 Months Ended 5 Months Ended 6 Months Ended 12 Months Ended
Dec. 26, 2019
Aug. 02, 2019
Feb. 28, 2019
Nov. 29, 2018
Mar. 26, 2018
Dec. 22, 2017
Aug. 28, 2017
Feb. 22, 2017
Feb. 28, 2019
Mar. 26, 2018
Dec. 31, 2017
Dec. 26, 2019
Aug. 28, 2017
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Feb. 19, 2020
Jul. 31, 2019
Jul. 30, 2019
Nov. 28, 2018
Dec. 21, 2017
Dec. 14, 2017
Feb. 16, 2017
Feb. 14, 2017
Equity, Class of Treasury Stock [Line Items]                                                
Share repurchase authorization                                     $ 3,000,000,000 $ 3,000,000,000.0 $ 3,000,000,000.0 $ 3,000,000,000 $ 2,250,000,000 $ 2,250,000,000
Shares received (in shares)                     3,040                          
Increase in treasury stock from share repurchases                     $ 750,000,000     $ 1,070,000,000 $ 1,090,000,000 $ 3,365,000,000                
Remaining share repurchase authorization at replacement                                     $ 1,030,000,000.00          
Common shares acquired in connection with employee stock plans (in shares)                           200 400 500                
Common shares acquired in connection with employee stock plans, amount                           $ 70,000,000 $ 116,000,000 $ 115,000,000                
Aggregate statutory capital and surplus in our state regulated insurance subsidiaries                           8,000,000,000.0 7,600,000,000                  
Aggregate minimum regulatory requirements of statutory capital and surplus                           5,900,000,000 5,200,000,000                  
Dividends that may be paid to the parent company without prior approval by state regulatory authorities in 2014                           1,000,000,000.0                    
Dividends that were paid to the parent company without prior approval by state regulatory authorities                           $ 1,800,000,000 $ 2,300,000,000 $ 1,400,000,000                
February 2017 ASR                                                
Equity, Class of Treasury Stock [Line Items]                                                
Accelerated share repurchase agreement amount                                             $ 1,500,000,000  
Accelerated share repurchase payment               $ 1,500,000,000                                
Shares received (in shares)             840 5,830         6,670                      
Increase in treasury stock from share repurchases               $ 1,200,000,000                                
Decrease in capital in excess of par value               $ 300,000,000                                
Average daily volume weighted-average share price of common stock during term of agreement (in USD per share)                         $ 224.81                      
Reclassification from capital in excess of par value to treasury stock             $ 300,000,000                                  
December 2017 ASR                                                
Equity, Class of Treasury Stock [Line Items]                                                
Accelerated share repurchase agreement amount                                         $ 1,000,000,000.0      
Accelerated share repurchase payment           $ 1,000,000,000.0                                    
Shares received (in shares)         460 3,280       3,740                            
Increase in treasury stock from share repurchases           $ 800,000,000                                    
Decrease in capital in excess of par value           $ 200,000,000                                    
Average daily volume weighted-average share price of common stock during term of agreement (in USD per share)                   $ 267.55                            
Reclassification from capital in excess of par value to treasury stock         $ 200,000,000                                      
November 2018 ASR                                                
Equity, Class of Treasury Stock [Line Items]                                                
Accelerated share repurchase agreement amount                                       $ 750,000,000        
Accelerated share repurchase payment       $ 750,000,000                                        
Shares received (in shares)     600 1,940         2,540                              
Increase in treasury stock from share repurchases       $ 600,000,000                                        
Decrease in capital in excess of par value       $ 150,000,000                                        
Average daily volume weighted-average share price of common stock during term of agreement (in USD per share)                 $ 295.15                              
Reclassification from capital in excess of par value to treasury stock     $ 150,000,000                                          
July 2019 ASR                                                
Equity, Class of Treasury Stock [Line Items]                                                
Accelerated share repurchase agreement amount                                   $ 1,000,000,000            
Accelerated share repurchase payment   $ 1,000,000,000                                            
Shares received (in shares) 700 2,700                   3,400                        
Increase in treasury stock from share repurchases   $ 800,000,000                                            
Decrease in capital in excess of par value   $ 200,000,000                                            
Average daily volume weighted-average share price of common stock during term of agreement (in USD per share)                       $ 296.19                        
Reclassification from capital in excess of par value to treasury stock $ 200,000,000                                              
Subsequent Event                                                
Equity, Class of Treasury Stock [Line Items]                                                
Remaining authorized amount                                 $ 2,000,000,000.0