Marketable Investments (Details 1) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Summary of Auction Rate Securities at their contractual maturity date
FY 2012, Total	$ 12,223
FY2013, Total	54,991
FY2014, Total	57,404
Thereafter, Total	32,928
Total available-for-sale securities	157,546	146,556
State and municipal obligations [Member]
Summary of Auction Rate Securities at their contractual maturity date
FY 2012, Total
FY2013, Total	6,477
FY2014, Total	10,442
Thereafter, Total	2,157
Total available-for-sale securities	19,076	9,482
Federal agency and corporate obligations [Member]
Summary of Auction Rate Securities at their contractual maturity date
FY 2012, Total	12,223
FY2013, Total	48,514
FY2014, Total	46,962
Thereafter, Total	20,982
Total available-for-sale securities	128,681	127,509
ARS [Member]
Summary of Auction Rate Securities at their contractual maturity date
FY 2012, Total
FY2013, Total
FY2014, Total
Thereafter, Total	9,789
Total available-for-sale securities	$ 9,789

- 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