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Fair Value Measurements (Details) (USD $)
In Thousands, unless otherwise specified |
3 Months Ended | |||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Mar. 31, 2014
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Mar. 31, 2014
Minimum
|
Mar. 31, 2014
Maximum
|
Mar. 31, 2014
Cash and Cash Equivalents
|
Dec. 31, 2013
Cash and Cash Equivalents
|
Mar. 31, 2014
Short-term investments
|
Mar. 31, 2014
Long-term investments
|
Mar. 31, 2014
Cash
Cash and Cash Equivalents
|
Dec. 31, 2013
Cash
Cash and Cash Equivalents
|
Mar. 31, 2014
Money market funds
Cash and Cash Equivalents
|
Dec. 31, 2013
Money market funds
Cash and Cash Equivalents
|
Mar. 31, 2014
Available-for-sale investments
|
Mar. 31, 2014
Available-for-sale investments
Cash and Cash Equivalents
|
Mar. 31, 2014
Available-for-sale investments
Short-term investments
|
Mar. 31, 2014
Available-for-sale investments
Long-term investments
|
Mar. 31, 2014
Asset-backed securities
|
Mar. 31, 2014
Asset-backed securities
Long-term investments
|
Mar. 31, 2014
Corporate bonds
|
Mar. 31, 2014
Corporate bonds
Short-term investments
|
Mar. 31, 2014
Corporate bonds
Long-term investments
|
Mar. 31, 2014
Commercial paper
|
Mar. 31, 2014
Commercial paper
Cash and Cash Equivalents
|
Mar. 31, 2014
Commercial paper
Short-term investments
|
Mar. 31, 2014
Measured on a recurring basis
|
Mar. 31, 2014
Measured on a recurring basis
Level 1
|
Dec. 31, 2013
Measured on a recurring basis
Level 1
|
Mar. 31, 2014
Measured on a recurring basis
Level 1
Money market funds
|
Dec. 31, 2013
Measured on a recurring basis
Level 1
Money market funds
|
Mar. 31, 2014
Measured on a recurring basis
Level 2
|
Mar. 31, 2014
Measured on a recurring basis
Level 2
Asset-backed securities
|
Mar. 31, 2014
Measured on a recurring basis
Level 2
Corporate bonds
|
Mar. 31, 2014
Measured on a recurring basis
Level 2
Commercial paper
|
Dec. 31, 2013
Carrying amount
|
Mar. 31, 2014
Carrying amount
Cash
|
Dec. 31, 2013
Carrying amount
Cash
|
Mar. 31, 2014
Carrying amount
Money market funds
|
Dec. 31, 2013
Carrying amount
Money market funds
|
Mar. 31, 2014
Fair value
Cash
|
|
| Fair Value Measurements | ||||||||||||||||||||||||||||||||||||||
| Cash and Cash Equivalents | $ 8,576 | $ 5,533 | $ 15,510 | $ 79,013 | $ 15,510 | $ 79,013 | $ 84,546 | $ 8,576 | $ 5,533 | $ 15,510 | $ 79,013 | $ 8,576 | ||||||||||||||||||||||||||
| Adjusted Cost | 61,531 | 4,466 | 37,085 | 19,980 | ||||||||||||||||||||||||||||||||||
| Unrealized Gains | 4 | 3 | 1 | |||||||||||||||||||||||||||||||||||
| Unrealized Losses | (37) | (1) | (34) | (2) | ||||||||||||||||||||||||||||||||||
| Fair Value | 2,799 | 36,592 | 22,107 | 4,465 | 19,412 | 17,642 | 2,799 | 17,180 | 61,498 | 4,465 | 37,054 | 19,979 | ||||||||||||||||||||||||||
| Total Cash and Cash Equivalents and Investments, Adjusted Cost | 85,617 | |||||||||||||||||||||||||||||||||||||
| Total assets, fair value | $ 26,885 | $ 84,546 | $ 36,592 | $ 22,107 | $ 85,584 | $ 15,510 | $ 79,013 | |||||||||||||||||||||||||||||||
| Maturity period of long-term investments | 1 year | 2 years | ||||||||||||||||||||||||||||||||||||