INVESTMENTS

The Company classifies the marketable securities in which it invests as available-for-sale securities. These securities are measured at fair value in the financial statements with unrealized gains or losses recorded in Other comprehensive income in the Company's Consolidated Statements of Comprehensive (Loss) Income. At the time the securities are sold or otherwise disposed of, gross realized gains and losses are included in Net (loss) income. Gross realized gains and losses are based on the carrying value (cost, net of discounts or premiums) of the sold investment. The amounts reclassified out of Other comprehensive income during the three months ended March 31, 2016 and 2015, were insignificant.

The amortized cost, gross unrealized gains, gross unrealized losses, and fair value of available-for-sale investment securities by major security type and class of security at March 31, 2016, and December 31, 2015 were as follows:



		Investments
(In thousands)		Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
2016
	Federal agency notes	$	248,200	$	49	$	(85	)	$	248,164
	Commercial paper	32,480		14		—			32,494
	Subtotal	280,680		63		(85		)	280,658
	Mutual funds	656		255		—			911
	Total	$	281,336	$	318	$	(85	)	$	281,569

2015
	Federal agency notes	$	285,276	$	—	$	(519	)	$	284,757
	Commercial paper	31,730		—		(58		)	31,672
	Subtotal	317,006		—		(577		)	316,429
	Mutual funds	482		261		—			743
	Total	$	317,488	$	261	$	(577	)	$	317,172

The mutual funds included in the investment table above are included in Other noncurrent assets on the Company's Consolidated Balance Sheets. Included in the investments balance at March 31, 2016 and December 31, 2015 is $18.5 million which has been reserved as collateral on the Company's undrawn letters of credit of approximately $17.5 million.

The maturities of available-for-sale securities at March 31, 2016 were as follows:



(In thousands)	Amortized cost		Fair value
Federal agency notes
Due in one year or less	$	172,432	$	172,433
Due after one year through two years	75,768		75,731
Total	$	248,200	$	248,164

Commercial paper
Due in one year or less	$	18,990	$	18,990
Due after one year through two years	13,490		13,504
Total	$	32,480	$	32,494

The Company has long-term investments in several Canadian junior exploration companies, recorded on the Company's Consolidated Balance Sheets at cost. These long-term investments totaled approximately $0.5 million at March 31, 2016 and December 31, 2015, and are recorded in Other noncurrent assets on the Company's Consolidated Balance Sheets.