|
Cash, Cash Equivalents and Marketable Securities Available-for-Sale (Duration Periods) (Details) (USD $)
In Millions, unless otherwise specified |
Mar. 31, 2015
|
|---|---|
| Amortized Cost | |
| Duration of one year or less | $ 327.9 |
| Duration of one through three years | 1,547.5 |
| Duration of three through five years | 99.9 |
| Total | 1,975.3 |
| Fair Value | |
| Duration of one year or less | 328.2 |
| Duration of one through three years | 1,550.2 |
| Duration of three through five years | 100.3 |
| Total | $ 1,978.7 |