Financial Instruments

Cash Equivalents

The Company had $654,739 and $509,811 of held-to-maturity securities with original maturities of three months or less, primarily consisting of corporate debt securities, classified as cash equivalents at June 30, 2015 and December 31, 2014, respectively. The Company's investments in held-to-maturity securities are held at amortized cost, which approximates fair value.

Available-for-Sale Marketable Securities

Investments in available-for-sale securities were classified as follows:



	June 30, 2015		December 31, 2014
Non-current	$	5,074	$	15,414
Total available-for-sale securities	$	5,074	$	15,414

The cost, gross unrealized gains, gross unrealized losses and fair value of the Company's available-for-sale securities were as follows:



	June 30, 2015
	Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Equity securities	$	3,802	$	1,272	$	—	$	5,074
Total available-for-sale securities	$	3,802	$	1,272	$	—	$	5,074



	December 31, 2014
	Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Equity securities	$	15,050	$	364	$	—	$	15,414
Total available-for-sale securities	$	15,050	$	364	$	—	$	15,414

As of June 30, 2015 and December 31, 2014, net unrealized gains on the Company's available-for-sale securities of $816 and $233, respectively, net of income tax expense of $456 and $131, respectively, were recorded in accumulated other comprehensive income. See Note 13 for the fair value hierarchy of the Company's available-for-sale securities.

The proceeds from sales and maturities of available-for-sale securities and the gross realized gains and losses included in the consolidated statements of operations are reflected in the table below. The cost of securities sold was determined using the specific identification method.



	Three Months Ended June 30,					Six Months Ended June 30,
	2015		2014			2015		2014
Proceeds from sales and maturities of securities	$	15,037	$	311,926		$	15,037	$	342,045
Gross realized gains	3,795		1,298			3,795		1,311
Gross realized losses	—		(61		)	—		(99		)