Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2013

Summary of Significant Accounting Policies [Abstract]

Summary of stock-based compensation allocated to research, development, general and administrative expenses

Total stock-based compensation expense included in the condensed consolidated statements of operations was allocated to research and development and general and administrative expenses as follows:

	March 31,
	2013		2012
Research and development	$	5,997	$	5,951
General and administrative		34,753		37,288
Total stock-based compensation	$	40,750	$	43,239