Investments (Narratives) (Details) - USD ($) $ in Millions	6 Months Ended
Sep. 30, 2020	Mar. 31, 2020
Insurance Regulatory Authorites:
Assets held by insurance regulators	$ 32.2	$ 30.8
Available for sale securities:
Fair value of sold available for sale securites	224.3
Available-for-sale securities, gross realized gains	3.1
Available-for-sale securities, gross realized losses	$ 1.0

Carrying amount of cash and investment securities on deposit with state regulatory authorities in connection with capital requirements.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 825
-Section 50
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=75763970&loc=SL75763979-209797

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
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