|
Summary of Significant Accounting Policies Realized Gain (Loss) on Short-Term Investments (Details) (USD $)
In Thousands, unless otherwise specified |
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2014
|
Dec. 31, 2013
|
Dec. 31, 2012
|
|
| Cash, Cash Equivalents, and Short-term Investments [Abstract] | |||
| Available-for-sale Securities, Gross Realized Gains | $ 48 | $ 166 | $ 14 |
| Available-for-sale Securities, Gross Realized Losses | (681) | (678) | (249) |
| Available-for-sale Securities, Gross Realized Gain (Loss) | $ (633) | $ (512) | $ (235) |