|
Fair Value Measurements (Details) (Money Market Funds [Member], USD $)
In Thousands, unless otherwise specified |
Mar. 31, 2015
|
Dec. 31, 2014
|
|---|---|---|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Investments fair value | $ 689,475 | $ 667,210 |
|
Level 1 [Member]
|
||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Investments fair value | 689,475 | 667,210 |
|
Level 2 [Member]
|
||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Investments fair value | 0 | 0 |
|
Level 3 [Member]
|
||
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
| Investments fair value | $ 0 | $ 0 |