Marketable Investment Securities - Schedule of Fair Value for Available-for-Sale Securities by Major Security Type and Class of Security (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Jun. 30, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 175,550	$ 270,224
Gross unrealized holding gains	117	383
Gross unrealized holding losses	(34)	(21)
Estimated fair value	175,633us-gaap_AvailableForSaleSecurities	270,586us-gaap_AvailableForSaleSecurities
Cash
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	45,092	45,181
Estimated fair value	45,092	45,181
Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	10,117	19,639
Gross unrealized holding gains		1
Estimated fair value	10,117	19,640
Total Cash And Cash Equivalents
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	55,209	64,820
Gross unrealized holding gains		1
Estimated fair value	55,209	64,821
Corporate Bonds And Notes
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	35,733	44,449
Gross unrealized holding gains	12	36
Gross unrealized holding losses	(11)	(11)
Estimated fair value	35,734	44,474
Municipal Bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	71,534	137,821
Gross unrealized holding gains	104	334
Gross unrealized holding losses	(22)	(3)
Estimated fair value	71,616	138,152
Federal Agency Issues
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	13,074	23,134
Gross unrealized holding gains	1	12
Gross unrealized holding losses	(1)	(7)
Estimated fair value	13,074	23,139
Total Available For Sale
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	120,341	205,404
Gross unrealized holding gains	117	382
Gross unrealized holding losses	(34)	(21)
Estimated fair value	$ 120,424	$ 205,765

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in equity securities classified as available-for-sale.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in equity securities classified as available-for-sale.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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-Name Accounting Standards Codification

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

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