Fair Value Measurements (Schedule Of Financial Assets And Liabilities Measured At Fair Value) (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 3,211,661	$ 5,497,788
Current Liabilities, fair value	(581,750)	(770,041)
Assets (Liabilities) Net, fair value	19,513,339	22,805,682
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	3,211,661	5,497,788
Assets (Liabilities) Net, fair value	3,211,661	5,497,788
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets (Liabilities) Net, fair value	16,883,429	18,077,935
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current Liabilities, fair value	(581,750)	(770,041)
Assets (Liabilities) Net, fair value	(581,750)	(770,041)
Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	3,211,661	5,497,788
Money Market Funds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	3,211,661	5,497,788
Accrued Consideration [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current Liabilities, fair value	(581,750)	(770,041)
Accrued Consideration [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Current Liabilities, fair value	(581,750)	(770,041)
Short-Term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	10,679,437	12,701,538
Short-Term Investments [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	10,679,437	12,701,538
Short-Term Investments [Member] | Certificates Of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4,477,193	7,258,768
Short-Term Investments [Member] | Certificates Of Deposit [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4,477,193	7,258,768
Short-Term Investments [Member] | Corporate Notes And Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4,557,917	3,800,143
Short-Term Investments [Member] | Corporate Notes And Bonds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4,557,917	3,800,143
Short-Term Investments [Member] | Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	1,644,327	1,642,627
Short-Term Investments [Member] | Commercial Paper [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	1,644,327	1,642,627
Long Term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	6,203,992	5,376,397
Long Term Investments [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	6,203,992	5,376,397
Long Term Investments [Member] | Certificates Of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	959,555	900,763
Long Term Investments [Member] | Certificates Of Deposit [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	959,555	900,763
Long Term Investments [Member] | Corporate Notes And Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	5,244,437	4,475,634
Long Term Investments [Member] | Corporate Notes And Bonds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 5,244,437	$ 4,475,634