Summary of Significant Accounting Policies (Tables)

6 Months Ended

12 Months Ended

Jun. 30, 2013

Dec. 31, 2012

Summary of Significant Accounting Policies [Abstract]

Estimated Useful Life of Property and Equipment

Property and equipment are depreciated using the straight-line method over the estimated useful lives of the respective assets as follows:

Asset Category	Estimated Useful Life (in Years)
Leasehold improvements	8 - 10
Furniture and office equipment	5
Computer and other equipment	3 - 5

Schedule of Share-based Compensation Expense

Share-based compensation expense for the three months ended June 30, 2013 and 2012 was:

	Three months ended June 30,
	2013		2012
Research and development	$	73,859	$	127,076
General and administrative		250,149		384,965
Total share-based compensation expense	$	324,008	$	512,041

Share-based compensation expense for the six months ended June 30, 2013 and 2012 was:

	Six months ended June 30,
	2013		2012
Research and development	$	162,493	$	244,143
General and administrative		490,096		816,562
Total share-based compensation expense	$	652,589	$	1,060,705

Share-based compensation expense for 2012, 2011 and 2010 is as follows:

	Year ended December 31,
	2012		2011		2010
Research and development	$	518,375	$	754,554	$	1,008,368
General and administrative		1,375,724		1,811,407		1,504,791
Total share-based compensation expense	$	1,894,099	$	2,565,961	$	2,513,159