Stock-Based Compensation Employee Stock Purchase Plan (Details) (Employee Stock [Member], USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Employee Stock [Member]
[Line Items]
Shares of stock sold to employees(1)	27,489	[1]	30,619	[1]	47,308	[1]	53,676	[1]
Weighted average fair value per ESPP award(2)	$ 6.37	[2]	$ 6.19	[2]	$ 6.69	[2]	$ 6.55	[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 and six months ended June 30.