Summary of Significant Accounting Policies (Narrative) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Jun. 30, 2013	Jun. 30, 2012
Summary of Significant Accounting Policies [Abstract]
Number of shares excluded from the computation of net loss per share			15,832,208	13,110,708
Reclassification of general and administrative expenses	$ 200	$ 100		$ 400
Reclassification of additional lease incentives				$ 1,100