Stock-Based Compensation (Details) (USD $)						12 Months Ended	96 Months Ended
	Dec. 31, 2011 2004 Equity Incentive Plan	Jul. 31, 2009 2008 Equity Incentive Plan	Dec. 31, 2008 2008 Equity Incentive Plan	Dec. 31, 2011 RSAs, certain members of Company's management	Dec. 31, 2007 RSAs, certain members of Company's management	Dec. 31, 2011 Employee stock purchase plan M period	Dec. 31, 2011 Employee stock purchase plan	Dec. 31, 2011 Performance-Contingent Restricted Stock Awards Senior management	Dec. 31, 2011 Performance-Contingent Restricted Stock Awards Officer	Dec. 31, 2011 Performance-Contingent Restricted Stock Units Senior management
Information related to stock-based compensation
Additional number of shares of common stock approved and authorized for issuance		200,000
Shares remaining available for issuance	2,090,098					556,546	556,546
Purchase price as a percentage of fair market value of stock						85.00%
Consecutive and overlapping offering periods (in months)						24
Number of offering periods						4
Duration of purchase period (in months)						6
Maximum contributions as a percentage of employee's eligible compensation						15.00%
Common stock, shares issued since plan inception in 2004							1,468,454
Shares of common stock approved and authorized for issuance (in shares)			500,000	1,168,000	71,000	2,025,000	2,025,000	1,290,000	25,000	210,000
Cumulative average sale price per share as of the period end (in dollars per share)							$ 10.15