Stock-Based Compensation Employee Stock Purchase Plan (Details) (Employee Stock [Member], USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Employee Stock [Member]
[Line Items]
Shares of stock sold to employees(1)	101,330	[1]	98,653	[1]	51,210	[1]
Weighted average fair value per ESPP award(2)	$ 6.29	[2]	$ 6.22	[2]	$ 9.27	[2]

[1] Stock sold to employees during each fiscal quarter under the ESPP is associated with the offering period ending on the last day of the previous fiscal quarter.

[2] Relating to awards associated with the offering periods during the years ended December 31.