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

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-Topic 944
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This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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The total amount of proceeds received for the sale of securities, categorized neither as held-to-maturity nor trading securities, during the reporting period.

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Stated maturity date of the mortgage loan receivable on real estate, in CCYY-MM-DD format.

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-Publisher FASB
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The stated interest rate on the mortgage loan receivable or the weighted average interest rate on a group of loans.

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Amount before tax of other than temporary impairment (OTTI) on investment in available-for-sale debt security, recognized in other comprehensive loss.

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Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.

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Investments (Narratives) (Details) - USD ($) $ in Millions	12 Months Ended
Investments (Narratives) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Assets held by insurance regulators				$ 32.4	$ 16.8
Fair value of sold available-for-sale securities	$ 163.7	$ 190.2	$ 150.7
Available-for-sale securities, gross realized gains	5.4	5.1	4.2
Available-for-sale securities, gross realized losses	0.3	2.2	0.6
Other-than-temporary impairments	0.0	0.0	$ 0.0
Mortgages [Member]
Real Estate [Abstract]
Allowance for probable losses and any unamortized premiums or discounts	$ 0.5	$ 0.5
Mortgages [Member] \| Minimum [Member]
Real Estate [Abstract]
Mortgage loan interest rate	4.30%
Mortgage loan maturity date	Dec. 31, 2018
Mortgages [Member] \| Maximum [Member]
Real Estate [Abstract]
Mortgage loan interest rate	6.90%
Mortgage loan maturity date	Dec. 31, 2036