Stock Compensation (Details 2) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014
Stock Option Plan
Compensation expense	$ 500	$ 1,000		$ 900	$ 2,100
Payments for employees' tax obligations				928	1,005
Restricted stock units
Stock Option Plan
Fair value of restricted stock units vested				$ 2,500	$ 2,700
Shares withheld to cover withholding tax of unit holders				35,714	34,573
Payments for employees' tax obligations				$ 900	$ 1,000
Incremental value of additional expense			$ 600