Comprehensive Income (Schedule of Reclassifications of Recognized Transactions out of AOCI) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Unrealized gains on available-for-sale securities	$ 3,824	$ (228)	$ 6,093	$ 311
Taxes	(7,187)	481	(30,344)	(34,976)
Reclassification of realized transactions, net of taxes	105,401	10,173	283,786	67,699
Reclassification out of Accumulated Other Comprehensive Income \| Unrealized gains on available-for-sale securities
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Unrealized gains on available-for-sale securities	113	14	2,279	235
Taxes	0	0	(776)	(51)
Reclassification of realized transactions, net of taxes	$ 113	$ 14	$ 1,503	$ 184

The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to pretax Income or Loss from continuing operations; income tax expense or benefit may include interest and penalties on tax uncertainties based on the entity's accounting policy.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

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-Name Statement of Financial Accounting Standard (FAS)

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 48

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Statement of Financial Accounting Standard (FAS)

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

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Reference 8: http://www.xbrl.org/2003/role/presentationRef

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-Publisher FASB

-Name Accounting Standards Codification

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-URI http://asc.fasb.org/extlink&oid=6519514

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Net Income

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-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

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Reference 12: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

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Reference 13: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

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-Publisher FASB

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-Publisher FASB

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-Publisher FASB

-Name Emerging Issues Task Force (EITF)

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+ Details