Investment Securities (Visa Class B Restricted Shares Narrative) (Details 8)	3 Months Ended
Jun. 30, 2019 shares
Visa Conversion Rate Swap Agreement
Net Investment Income [Line Items]
Debt Instrument, Convertible, Conversion Ratio	1.6298
Equity securities remaining, shares	83,014
Visa Class A Unrestricted Securities
Net Investment Income [Line Items]
Equity securities remaining, shares	135,296

Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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