Fair Value Measurements Schedule Of Financial Assets And Liabilities Measured At Fair Value On A Recurring Basis (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments, Owned, State and Municipal Government Obligations, at Fair Value	$ 84,313	$ 70,525
Available-for-sale Securities, Failed Auction, Value	336	363
Available-for-sale Securities, Fair Value Disclosure	84,649	70,888
Foreign Currency Contracts, Liability, Fair Value Disclosure	181	99
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	181	99
Financial Instruments, Owned, at Fair Value	84,830	70,987
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments, Owned, State and Municipal Government Obligations, at Fair Value	84,313	70,525
Available-for-sale Securities, Failed Auction, Value	0	0
Available-for-sale Securities, Fair Value Disclosure	84,313	70,525
Foreign Currency Contracts, Liability, Fair Value Disclosure	181	99
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	181	99
Financial Instruments, Owned, at Fair Value	84,494	70,624
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments, Owned, State and Municipal Government Obligations, at Fair Value	0	0
Available-for-sale Securities, Failed Auction, Value	0	0
Available-for-sale Securities, Fair Value Disclosure	0	0
Foreign Currency Contracts, Liability, Fair Value Disclosure	0	0
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	0	0
Financial Instruments, Owned, at Fair Value	0	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments, Owned, State and Municipal Government Obligations, at Fair Value	0	0
Available-for-sale Securities, Failed Auction, Value	336	363
Available-for-sale Securities, Fair Value Disclosure	336	363
Foreign Currency Contracts, Liability, Fair Value Disclosure	0	0
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	0	0
Financial Instruments, Owned, at Fair Value	$ 336	$ 363

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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Derivative instrument obligations meeting the definition of a liability which the Company is a party to as of the balance sheet date.

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- Definition

The aggregate fair value as of the balance sheet date of financial instruments and other positions owned by the entity including: (1) mortgages, mortgage-backed and asset backed securities; (2) US government and agency obligations; (3) state and municipal government obligations; (4) other sovereign government debt; (5) corporate obligations; (6) corporate equities; (7) principal investments; (8) derivative contracts; and (9) physical commodities. Includes both pledged and unpledged holdings.

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