Related Party Transactions (Details) (USD $)	Sep. 30, 2012	Dec. 31, 2011		Sep. 30, 2011	Dec. 31, 2010
Related Party Transaction [Line Items]
Cash and cash equivalents	$ 9,484,000	$ 13,709,000	[1]	$ 13,716,000	$ 4,147,000
Amount invested in United States Treasury money market funds	$ 6,738,000	$ 10,087,000
Percentage of stockholders controlled by entity (in hundredths)	10.00%	10.00%

[1] The Condensed Consolidated Balance Sheet as of December 31, 2011, has been derived from the audited consolidated financial statements at that date, but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.