Contingent Consideration (Details) (USD $) In Thousands	1 Months Ended	3 Months Ended	6 Months Ended
	Apr. 30, 2011	Jun. 30, 2011	Jun. 30, 2011
Contingent Consideration
Contingent consideration payment due in 2011	$ 40,000
Maximum aggregate undiscounted amount of contingent consideration		59,000	59,000
Remaining contingent consideration liability adjusted through operating income		17,813	17,813
Changes in net income due to adjustment of remaining contingent consideration liability		$ 11,200