Receivables (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	$ 1,053	$ 597
Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	961	511
Medicaid Solutions Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	39	37
Other segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	53	49
California | Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	174	104
Florida | Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	79	22
Illinois | Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	81	35
Michigan | Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	71	39
New Mexico | Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	78	51
New York | Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	33	0
Ohio | Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	133	66
Puerto Rico | Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	82	33
South Carolina | Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	12	6
Texas | Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	62	56
Utah | Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	32	18
Washington | Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	94	53
Wisconsin | Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	27	22
Direct delivery and other | Health Plans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	$ 3	$ 6