Fixed income securities (Details) (USD $)	12 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2010
Proceeds from Sale of Fixed Income Securities [Abstract]
Proceeds from Sale or Maturity of Available-for-sale Securities	$ 68,503,000	$ 72,703,000	$ 16,191,000
Proceeds from sale or maturity of Held-to-maturity securities	0	14,295,000	0
Available-for-sale Securities, Gross Realized Gain (Loss), Excluding Other than Temporary Impairments [Abstract]
Available-for-sale Securities, Gross Realized Gains	100,000	300,000
Short-term investments: due in one year or less
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	40,213,000	43,227,000
Unrealized Gains	208,000	430,000
Estimated Fair Value	40,421,000	43,657,000
Non-current assets: due in one through five years
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,924,000	49,625,000
Unrealized Gains	5,000	769,000
Estimated Fair Value	$ 11,929,000	$ 50,394,000

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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- Definition

The cash inflow associated with the sale or maturity (principal being due) of securities not classified as either held-to-maturity securities or trading securities which are classified as available-for-sale securities.

+ References

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- Definition

The cash inflow associated with the sale or maturity of securities for which the entity has both the ability and intent to hold the instrument until maturity.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details