Fair Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value Measurements [Line Items]
Private equity investments	$ 153,411	$ 147,406
Significant Unobservable Inputs (Level 3)
Fair Value Measurements [Line Items]
Auction Rate Securities Available For Sale	1,900
Private equity investments	$ 153,411	$ 147,406

The fair value as of the balance sheet date of firm holdings in private equity, mezzanine, venture capital, merchant banking, real estate and special situations investments. Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 320
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=35711157&loc=d3e42546-110969

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant