Marketable Securities Summary of Marketable Securities Including Accrued Interest Receivable (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Sep. 30, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 97,666	$ 90,404
Gross Unrealized Gains	81	57
Gross Unrealized Losses	(95)	(70)
Fair Value	97,652	90,391
U.S. Treasury securities and obligations of U.S. government agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	20,179	19,528
Gross Unrealized Gains	3	6
Gross Unrealized Losses	(22)	(13)
Fair Value	20,160	19,521
Corporate securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	42,801	35,045
Gross Unrealized Gains	44	11
Gross Unrealized Losses	(55)	(47)
Fair Value	42,790	35,009
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,075	1,093
Gross Unrealized Gains	26	25
Gross Unrealized Losses	(5)	(1)
Fair Value	1,096	1,117
Other debt securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	34	88
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	34	88
Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	25,026	25,199
Gross Unrealized Gains	8	15
Gross Unrealized Losses	(11)	(7)
Fair Value	25,023	25,207
Bank certificate of deposits
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,551	9,451
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2)	(2)
Fair Value	$ 8,549	$ 9,449

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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