Fair value measurements - Investments in Company-Sponsored Funds (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Investment Holdings [Line Items]
Fair Value	$ 5,521	$ 4,836
Unfunded Commitments	4,035	1,238
Hedge Funds
Investment Holdings [Line Items]
Fair Value	900	1,126
Unfunded Commitments	0	0
Private Equity Funds
Investment Holdings [Line Items]
Fair Value	4,621	3,710
Unfunded Commitments	$ 4,035	$ 1,238

The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=SL6742756-110258

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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