XML 62 R49.htm IDEA: XBRL DOCUMENT v3.8.0.1
Medical Claims and Benefits Payable - Components of Change in Medical Claims and Benefits Payable (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Insurance Claims    
Medical claims and benefits payable, beginning balance $ 2,192 $ 1,929
Components of medical care costs related to:    
Current period 3,963 4,253
Prior periods (241) (142)
Total medical care costs 3,722 4,111
Change in non-risk provider payables 45 (96)
Payments for medical care costs related to:    
Current period 2,498 2,683
Prior periods 1,438 1,335
Total paid 3,936 4,018
Medical claims and benefits payable, ending balance $ 2,023 $ 1,926
Benefit from prior period as a percentage of:    
Balance at beginning of period 11.00% 7.40%
Premium revenue, trailing twelve months 1.30% 0.80%
Medical care costs, trailing twelve months 1.40% 0.90%