Investments in Available-for-Sale Securities

3 Months Ended

Mar. 31, 2016

Available-for-sale Securities [Abstract]

Investments in Available-for-Sale Securities

Investments in Available-for-Sale Securities

The Company has invested in marketable debt securities, primarily highly liquid investment grade corporate bonds. These investments are held in the custody of a major financial institution. These securities, along with the Company's investments in marketable equity securities, are classified as available-for-sale securities and, accordingly, the unrealized gains and losses are recorded through other comprehensive income.

The Company's investments in available-for-sale marketable securities are as follows:

	March 31, 2016
										Balance Sheet
										Classification
			Gross Unrealized					Fair		Short-Term		Other
	Cost Basis		Gains		Losses			Value		Investments		Assets
	(In thousands)
Available-for-sale:
U.S. government and agency securities	$	47,001	$	66	$	—		$	47,067	$	47,067	$	—
Corporate notes and bonds	$	151,782	$	38	$	(99	)	$	151,721	$	151,721	$	—
Equity securities	1,049		676		—			1,725		—		1,725
Total Investments	$	199,832	$	780	$	(99	)	$	200,513	$	198,788	$	1,725

	December 31, 2015
										Balance Sheet
										Classification
			Gross Unrealized					Fair		Short-Term		Other
	Cost Basis		Gains		Losses			Value		Investments		Assets
	(In thousands)
Available-for-sale:
U.S. government and agency securities	$	10,007	$	—	$	(12	)	$	9,995	$	9,995	$	—
Corporate notes and bonds	$	190,496	$	—	$	(299	)	$	190,197	$	190,197	$	—
Equity securities	3,938		668		(2,888		)	1,718		—		1,718
Total Investments	$	204,441	$	668	$	(3,199	)	$	201,910	$	200,192	$	1,718

The aggregate fair value of investments with unrealized losses that were owned for less than a year was $78.5 million and $184.6 million at March 31, 2016 and December 31, 2015, respectively. The aggregate fair value of investments with unrealized losses that were owned for over a year, and were also in a continuous unrealized loss position during that time, was $8.0 million and $15.8 million at March 31, 2016 and December 31, 2015, respectively. During the quarter, the Company identified and recorded an other-than-temporary impairment charge of $2.9 million which represented the unrealized loss in accumulated other comprehensive income related to an individual available-for-sale security. This charge is included in the line item "Asset impairment and mine closure costs" within the Condensed Consolidated Statement of Operations. The unrealized losses in the Company's portfolio at March 31, 2016 are the result of normal market fluctuations. The Company does not currently intend to sell these investments before recovery of their amortized cost base.

The debt securities outstanding at March 31, 2016 have maturity dates ranging from the second quarter of 2016 through the third quarter of 2017. The Company classifies its investments as current based on the nature of the investments and their availability to provide cash for use in current operations.