Investment Securities - Investment in MediaAlpha textual (Details) - Marketing Technology (MediaAlpha) $ / shares in Units, $ in Millions	Mar. 31, 2022 USD ($) $ / shares
Subsidiary, Sale of Stock [Line Items]
Share price (in usd per share) \| $ / shares	$ 16.55
Investment owned, balance \| $	$ 280.4

For investments which are quantified by principal amount, the principle balance held at close of period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 210
-Section 50
-Paragraph 6
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=99383244&loc=d3e12121-115841

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-12B(Column B))
-URI http://asc.fasb.org/extlink&oid=120401592&loc=d3e611197-123010

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant