Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity (Details)

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Stockholders' Equity (Details) - USD ($)
1 Months Ended 12 Months Ended
Jan. 23, 2020
May 31, 2018
Apr. 30, 2018
Mar. 31, 2018
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Oct. 31, 2019
Dec. 31, 2009
Subsidiary, Sale of Stock [Line Items]                  
Preferred stock, shares authorized (in shares)         10,000,000 10,000,000      
Preferred stock, par value (in usd per share)         $ 0.001 $ 0.001      
Preferred stock, shares outstanding (in shares)         0 0      
Stock repurchase program, shares authorized to repurchase (in shares)                 16,000,000.0
Remaining number of shares available to be repurchased (in shares)         14,200,000 6,700,000      
Stock repurchase program increase amount               $ 500,000,000  
Centene closing stock price (in usd per share)               $ 66.76  
Stock repurchase program, additional shares authorized to be repurchased               7,500,000  
Common stock repurchases (in shares)         1,000,000 1,000,000      
Payments for repurchase of common stock         $ 75,000,000 $ 71,000,000 $ 65,000,000    
Common stock issued for stock offering           $ 2,779,000,000      
MHM Services                  
Subsidiary, Sale of Stock [Line Items]                  
Shares issued in business acquisition (in shares)     3,000,000            
Equity value issued in business acquisition     $ 183,000,000            
Community Medical Holdings Corp                  
Subsidiary, Sale of Stock [Line Items]                  
Shares issued in business acquisition (in shares)       3,000,000          
Equity value issued in business acquisition       $ 149,000,000          
Interpreta Holdings                  
Subsidiary, Sale of Stock [Line Items]                  
Shares issued in business acquisition (in shares)       3,000,000          
Equity value issued in business acquisition       $ 175,000,000          
Percentage of voting interests acquired       61.00%          
Public Stock Offering                  
Subsidiary, Sale of Stock [Line Items]                  
Shares issued in registered offering (in shares)   53,200,000              
Common stock issued for stock offering   $ 2,860,000,000              
Net proceeds from stock offering   $ 2,779,000,000              
Over-Allotment Option                  
Subsidiary, Sale of Stock [Line Items]                  
Over allotment option to purchase additional shares, percentage   10.00%              
Subsequent Event                  
Subsidiary, Sale of Stock [Line Items]                  
Centene closing stock price (in usd per share) $ 66.76                
Subsequent Event | WellCare                  
Subsidiary, Sale of Stock [Line Items]                  
Shares issued in business acquisition (in shares) 171,000,000                
Equity value issued in business acquisition $ 11,431,000,000