Marketable Securities

6 Months Ended

Mar. 31, 2022

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

4. Marketable Securities

The Company invests in marketable securities that are classified as available-for-sale and records them at fair value in the accompanying unaudited Consolidated Balance Sheets. Marketable securities reported as current assets represent investments that mature within one year from the balance sheet date. Long-term marketable securities represent investments with maturity dates greater than one year from the balance sheet date.

Unrealized gains and losses are excluded from earnings and reported as a separate component of “accumulated other comprehensive income, net of tax” in the accompanying unaudited Consolidated Balance Sheets until the security is sold or matures. Gains or losses realized from sales of marketable securities are computed based on the specific identification method and recognized as a component of "Other income (expenses), net" in the accompanying unaudited Consolidated Statements of Operations. There were insignificant sales of marketable securities for the three and six months ended March 31, 2022 and 2021.

The following is a summary of the amortized cost and the fair value, including accrued interest receivable as well as unrealized holding gains (losses) on the short-term and long-term marketable securities as of March 31, 2022 and September 30, 2021 (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Losses		Gains		Fair Value
March 31, 2022:
U.S. Treasury securities and obligations of U.S. government agencies	$	720,648	$	(1,185)	$	18	$	719,481
Corporate securities		258,862		(1,899)		—		256,963
Municipal securities		100,518		(230)		—		100,288
	$	1,080,028	$	(3,314)	$	18	$	1,076,732
September 30, 2021:
Bank certificates of deposits	$	30	$	—	$	—	$	30
Corporate securities		3,624		—		—		3,624
Other debt securities		25		—		—		25
	$	3,679	$	—	$	—	$	3,679

The fair values of the marketable securities by contractual maturities at March 31, 2022 are presented below (in thousands):

	Amortized
	Cost			Fair Value
Due in one year or less	$	817,223	$	816,512
Due after one year through five years		259,382		256,797
Due after five years through ten years		—		—
Due after ten years		3,422		3,423
Total marketable securities	$	1,080,027	$	1,076,732

Expected maturities could differ from contractual maturities because the security issuers may have the right to prepay obligations without prepayment penalties.

The Company reviews the marketable securities for impairment at each reporting period to determine if any of the securities have experienced an other-than-temporary decline in fair value. The Company considers factors, such as the length of time and extent to which the market value has been less than the cost, the financial condition and near-term prospects of the issuer, the Company’s intent to sell, or whether it is more likely than not it will be required to sell the investment before recovery of its amortized cost basis. If the Company believes that an other-than-temporary decline in fair value has occurred, it writes down the investment to its fair value and recognizes the credit loss in earnings and the non-credit loss in accumulated other comprehensive income or loss. Securities in an unrealized loss position as of March 31, 2022 were $939.1 million. There were no securities in an unrealized loss position as of September 30, 2021.