Stock-Based Compensation Employee Stock Purchase Plan (Details) (Employee Stock [Member], USD $)	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Employee Stock [Member]
[Line Items]
Shares of stock sold to employees(1)	19,819	[1]	23,057	[1]
Weighted average fair value per ESPP award(2)	$ 6.96	[2]	$ 6.81	[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 period during the three months ended March 31.