This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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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.

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- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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- 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 Trading Securities which consist of all investments in certain debt and equity securities that are bought and held principally for the purpose of selling them in the near term (thus held for only a short period of time) or for which an entity has elected the fair value option. Trading generally reflects active and frequent buying and selling, and trading securities are generally used with the objective of generating profits on short-term differences in price, but this category of investments may also include items which are not intended to be sold in the near term or for which the fair value option has been elected.

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Investment Securities (Details) (USD $) In Thousands, unless otherwise specified					12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2010 Commercial paper	Dec. 31, 2010 U.S. treasury bills	Dec. 31, 2010 U.S. treasury bills Less than D	Dec. 31, 2011 Mortgage-Backed Securities and Bonds	Dec. 31, 2011 Fixed income securities: Mortgage-backed securities	Dec. 31, 2010 Fixed income securities: Mortgage-backed securities	Dec. 31, 2011 Municipal bonds	Dec. 31, 2010 Municipal bonds	Dec. 31, 2011 Corporate bonds	Dec. 31, 2010 Corporate bonds	Dec. 31, 2011 Common Stock	Dec. 31, 2010 Common Stock	Dec. 31, 2011 Affiliated mutual funds	Dec. 31, 2010 Affiliated mutual funds
Investment Securities
Available for sale securities, Amortized cost	$ 99,907	$ 88,333		$ 56,961			$ 9	$ 10	$ 2,549	$ 2,729	$ 45,893				$ 51,456	$ 28,633
Available for sale securities, Unrealized gains	2,910	5,664					2	2			170				2,738	5,662
Available for sale securities, Unrealized losses	(5,481)	(222)							(13)	(185)	(89)				(5,379)	(37)
Available for sale securities, Fair value	97,336	93,775		56,961			11	12	2,536	2,544	45,974				48,815	34,258
Trading securities
Trading securities, Fair value	38,161	98,836	4,997	60,958		17,882	63	73	500	487	17,319	50	37	201	20,242	32,070
Investment securities	$ 135,497	$ 192,611
U.S. treasury bills maturity period (in days)					180