- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References+ Details

Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Value Measurements
Amount of transfers of financial assets between Level 1 and Level 2 measures	$ 0
Assets:
Short term investments:	125,592	200,577
Available-for-sale equity securities
Assets:
Short term investments:	97,118	174,610
Recurring
Assets:
Total short-term investments	125,592
Recurring \| Available-for-sale equity securities
Assets:
Short term investments:	97,118
Recurring \| Commercial paper and CDs
Assets:
Short term investments:	88
Recurring \| Corporate debt securities
Assets:
Short term investments:	26,550
Recurring \| Mortgage-backed debt securities
Assets:
Short term investments:	218
Recurring \| Mortgage-CMO debt securities
Assets:
Short term investments:	253
Recurring \| Asset-backed debt securities
Assets:
Short term investments:	1,365
Recurring \| Level 1
Assets:
Total short-term investments	97,709
Recurring \| Level 1 \| Available-for-sale equity securities
Assets:
Short term investments:	96,256
Recurring \| Level 1 \| Commercial paper and CDs
Assets:
Short term investments:	88
Recurring \| Level 1 \| Asset-backed debt securities
Assets:
Short term investments:	1,365
Recurring \| Level 2
Assets:
Total short-term investments	27,883
Recurring \| Level 2 \| Available-for-sale equity securities
Assets:
Short term investments:	862
Recurring \| Level 2 \| Corporate debt securities
Assets:
Short term investments:	26,550
Recurring \| Level 2 \| Mortgage-backed debt securities
Assets:
Short term investments:	218
Recurring \| Level 2 \| Mortgage-CMO debt securities
Assets:
Short term investments:	$ 253