Stockholders' Equity, ATM Program and 401(k) Matching Contribitions (Details) (USD $)	12 Months Ended			0 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Mar. 12, 2012 ATM Program [Member]	Mar. 31, 2012 ATM Program [Member]	Dec. 31, 2012 ATM Program [Member]
Stockholders' Equity [Line Items]
Period of agency agreement						2 years
Maximum value of potential common stock available for issue						$ 15,000,000
Percentage sales commission on shares (in hundredths)						3.00%
Issuance of common stock, financing (in shares)				350,374	350,374
Issuance of common stock, financing				1,600,000
Net proceeds from issuance of stock				1,500,000	1,500,000
Issuance of common stock, 401(k) employer match (in shares)	316,543	265,185	61,158
Expense associated with 401(k) plan	$ 800,000	$ 500,000	$ 200,000