|
Investments in Available-for-Sale Securities (Details) (USD $)
In Thousands, unless otherwise specified
|
Mar. 31, 2015
|
Dec. 31, 2014
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Debt Securities, Current |
$ 249,518 |
$ 248,954 |
| Total Investments, Cost Basis |
256,583 |
257,500 |
| Total Investments, Accumulated Gross Unrealized Gains |
2,877 |
4,125 |
| Total Investments, Accumulated Gross Unrealized Losses |
(5,987) |
(7,526) |
| Total Investments |
253,473 |
254,099 |
| Short-term Investments [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total Investments, Current |
249,518 |
248,954 |
| Other Assets [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Total Investments, Noncurrent |
3,955 |
5,145 |
| Corporate Debt Securities [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Debt Securities, Cost Basis |
252,673 |
253,590 |
| Debt Securities, Accumulated Gross Unrealized Gains |
2 |
0 |
| Debt Securities, Accumulated Gross Unrealized Losses |
(3,157) |
(4,636) |
| Debt Securities |
249,518 |
248,954 |
| Corporate Debt Securities [Member] | Short-term Investments [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Debt Securities, Current |
249,518 |
248,954 |
| Corporate Debt Securities [Member] | Other Assets [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Debt Securities, Noncurrent |
0 |
0 |
| Equity Securities [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Equity Securities, Cost Basis |
3,910 |
3,910 |
| Equity Securities, Accumulated Gross Unrealized Gains |
2,875 |
4,125 |
| Equity Securities, Accumulated Gross Unrealized Losses |
(2,830) |
(2,890) |
| Equity securities |
3,955 |
5,145 |
| Equity Securities [Member] | Short-term Investments [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Equity Securities, Current |
0 |
0 |
| Equity Securities [Member] | Other Assets [Member] |
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
| Equity Securities, Noncurrent |
$ 3,955 |
$ 5,145 |