Borrowings (Interest Rates and Company Borrowings) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Interest and debt expense:
Weighted average interest rate during the quarter	1.66%	3.09%	1.65%	3.44%
Interest rate at quarter end	1.65%	2.95%	1.65%	2.95%
Maximum amount outstanding during the quarter	$ 1,082,000	$ 1,025,000	$ 1,175,000	$ 1,025,000
Average amount outstanding during the quarter	1,057,380	1,014,511	1,092,382	995,508
Facility fees	$ 91	$ 40	$ 185	$ 147

The average effective interest rate during the reporting period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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Average amount borrowed under the credit facility during the period.

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Amount of the fees associated with providing collateral for the credit facility.

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The effective interest rate during the reporting period.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
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