Cash, Cash Equivalents and Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2013

Investments in Debt Securities

Investments in debt securities consisted of the following at March 31, 2013:

	March 31, 2013
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Marketable securities:
U.S. Government and agency securities	$	2,084,913	$	208	$	—		$	2,085,121
Corporate and other debt securities		17,242,580		11,159		(1,736	)		17,252,003
		19,327,493		11,367		(1,736	)		19,337,124
Long-term marketable securities:
U.S. Government and agency securities		5,324,930		2,457		(209	)		5,327,178
Corporate and other debt securities		820,643		306		(38	)		820,911
		6,145,573		2,763		(247	)		6,148,089
Total	$	25,473,066	$	14,130	$	(1,983	)	$	25,485,213

Investments in debt securities consisted of the following at December 31, 2012:

	December 31, 2012
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Marketable securities:
U.S. Government and agency securities	$	2,000,897	$	353	$	(7	)	$	2,001,243
Corporate and other debt securities		8,835,098		8,854		—			8,843,952
		10,835,995		9,207		(7	)		10,845,195
Long-term marketable securities:
U.S. Government and agency securities		5,198,264		2,747		—			5,201,011
Corporate and other debt securities		4,711,679		3,525		(1,360	)		4,713,844
		9,909,943		6,272		(1,360	)		9,914,855
Total	$	20,745,938	$	15,479	$	(1,367	)	$	20,760,050

Contractual Maturities of Debt Securities

The contractual maturities of debt securities at March 31, 2013 were as follows:

	Amortized Cost		Fair Value
Due in 1 year or less	$	19,327,496	$	19,337,124
Due in 1 to 2 years		6,145,573		6,148,089
	$	25,473,069	$	25,485,213