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Fair Value of Financial Instruments (Fair Value Hierarchy) (Details) (USD $)
In Thousands, unless otherwise specified
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Dec. 31, 2013
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Dec. 31, 2012
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
$ 105,133 |
$ 94,843 |
|
Level 1 | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
0 |
0 |
|
Level 2 | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
105,133 |
94,843 |
|
Level 3 | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
0 |
0 |
|
Fair Value | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
105,133 |
94,843 |
|
Commercial paper
|
|
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| Assets, Fair Value Disclosure [Abstract] |
|
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| Available-for-sale securities, fair value |
47,488 |
32,376 |
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Commercial paper | Level 1 | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
0 |
0 |
|
Commercial paper | Level 2 | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
47,488 |
32,376 |
|
Commercial paper | Level 3 | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
0 |
0 |
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Commercial paper | Fair Value | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
47,488 |
32,376 |
|
U.S. government agencies
|
|
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| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
18,837 |
62,467 |
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U.S. government agencies | Level 1 | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
0 |
0 |
|
U.S. government agencies | Level 2 | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
18,837 |
62,467 |
|
U.S. government agencies | Level 3 | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
0 |
0 |
|
U.S. government agencies | Fair Value | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
18,837 |
62,467 |
|
Municipal bonds
|
|
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| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
1,128 |
|
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Municipal bonds | Level 1 | Recurring Basis
|
|
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| Assets, Fair Value Disclosure [Abstract] |
|
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| Available-for-sale securities, fair value |
0 |
|
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Municipal bonds | Level 2 | Recurring Basis
|
|
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| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
1,128 |
|
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Municipal bonds | Level 3 | Recurring Basis
|
|
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| Assets, Fair Value Disclosure [Abstract] |
|
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| Available-for-sale securities, fair value |
0 |
|
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Municipal bonds | Fair Value | Recurring Basis
|
|
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| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
1,128 |
|
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Corporate bonds
|
|
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| Assets, Fair Value Disclosure [Abstract] |
|
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| Available-for-sale securities, fair value |
32,179 |
|
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Corporate bonds | Level 1 | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
0 |
|
|
Corporate bonds | Level 2 | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
32,179 |
|
|
Corporate bonds | Level 3 | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
0 |
|
|
Corporate bonds | Fair Value | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
32,179 |
|
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Asset-backed securities
|
|
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| Assets, Fair Value Disclosure [Abstract] |
|
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| Available-for-sale securities, fair value |
5,501 |
|
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Asset-backed securities | Level 1 | Recurring Basis
|
|
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| Assets, Fair Value Disclosure [Abstract] |
|
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| Available-for-sale securities, fair value |
0 |
|
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Asset-backed securities | Level 2 | Recurring Basis
|
|
|
| Assets, Fair Value Disclosure [Abstract] |
|
|
| Available-for-sale securities, fair value |
5,501 |
|
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Asset-backed securities | Level 3 | Recurring Basis
|
|
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| Assets, Fair Value Disclosure [Abstract] |
|
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| Available-for-sale securities, fair value |
0 |
|
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Asset-backed securities | Fair Value | Recurring Basis
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|
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| Assets, Fair Value Disclosure [Abstract] |
|
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| Available-for-sale securities, fair value |
$ 5,501 |
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