Stock-Based Compensation Employee Stock Purchase Plan (Details) (Employee Stock [Member], USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Employee Stock [Member]
[Line Items]
Shares of stock sold to employees	25,567	[1]	10,736	[1]	42,625	[1]	23,086	[1]
Weighted average fair value per ESPP award	$ 7.22	[2]	$ 9.27	[2]	$ 7.88	[2]	$ 9.95	[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.