|
Segment Information - Revenue by Product Type (Details) (USD $)
In Millions, unless otherwise specified |
3 Months Ended | |
|---|---|---|
|
Mar. 31, 2015
|
Mar. 31, 2014
|
|
| Revenue from External Customer [Line Items] | ||
| Premiums and fees, mail order pharmacy revenues and other revenues | $ 9,118 | $ 8,177 |