Stock-Based Compensation Employee Stock Purchase Plan (Details) (Employee Stock [Member], USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Employee Stock [Member]
[Line Items]
Shares of stock sold to employees	22,739	[1]	22,518	[1]	76,415	[1]	65,143	[1]
Weighted average fair value per ESPP award	$ 6.47	[2]	$ 4.43	[2]	$ 6.52	[2]	$ 5.56	[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 nine months ended September 30.