Investments and Derivative Instruments - Narrative (Details) (USD $)	Dec. 01, 2012	Mar. 31, 2013 Preferred Stock	Jun. 30, 2012 Preferred Stock
Schedule of Trading Securities and Other Trading Assets
Notional amount of interest rate derivatives	$ 10,000,000
Fixed future interest rate effective due to swap	0.48%
Fair value of trading securities in unrealized gain position		18,200,000	16,500,000
Fair value of trading securities in unrealized loss position		$ 2,563,000	$ 2,891,000

Aggregate notional amount of interest rate derivatives, which relates to the currency amount specified in the interest rate derivative instruments.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant