Cash, Cash Equivalents, and Investments (Tables)

6 Months Ended

Jun. 30, 2012

Cash, cash equivalents, and investments [Abstract]

Summary of cash, cash equivalents and held-to-maturity investments by type

	June 30, 2012									December 31, 2011
	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value		Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Cash and money market funds	$	17,970,019	$	—	$	—		$	17,970,019	$	21,300,733	$	—	$	—		$	21,300,733
Commercial paper		3,506,263		—		(2,831	)		3,503,432		5,008,189		—		(3,238	)		5,004,951
Certificates of deposit		1,680,000		—		(1,488	)		1,678,512		100,000		—		(69	)		99,931
Total cash, cash equivalents and investments	$	23,156,282	$	—	$	(4,319	)	$	23,151,963	$	26,408,922	$	—	$	(3,307	)	$	26,405,615

Summarized classification of short term and Long term investments

	June 30, 2012		December 31, 2011
Cash	$	5,190,178	$	6,061,523
Cash equivalents		12,779,841		15,239,210
Total cash and cash equivalents		17,970,019		21,300,733
Short-term investments		5,186,263		5,108,189
Total cash, cash equivalents and investments	$	23,156,282	$	26,408,922