Summary of Investments (Details 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Dec. 31, 2012
Summary of Investments
Limited partnership and other corporation interests	$ 113,610	$ 124,814
Interest in various upper-tier LIHLPs (as a percent)	99.00%
Nature and activities of the VIEs and the effect on financial statements
Carrying value in relation to the activities of the VIEs	61,418	71,370
Maximum exposure to loss in relation to the activities of the VIEs	61,418	71,370
Special deposits and securities lending
Fair value of securities on deposit with governmental authorities	15,581	15,791
Securities loaned to third parties at amortized cost	43,806	138,654
Estimated fair value of securities loaned to third parties	44,230	138,297
Restricted cash collateral received	$ 45,813	$ 142,022

Carrying value of securities loaned to other entities.

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Amount of cash subject to withdrawal restrictions, restricted deposits held as compensating balances, and cash and securities segregated in compliance with regulations (such as cash deposited in a special reserve account for the exclusive benefit of customers).

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The amount of cash received as security in return for loaning securities to another party.

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Total investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership.

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The number of units or percentage investment held by one or more members or limited partners of the LLC or LP.

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The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

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