Basis of Presentation Schedule of Error Corrections and Prior Period Adjustment - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2015	Sep. 30, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Gross profit	$ 100,341		$ 95,553		$ 276,157	$ 269,233
Income from operations	35,249		32,218		86,535	83,956
Net income	$ 21,595	$ 10,380	$ 20,614		$ 53,156	$ 53,151
Restatement Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Gross profit				$ 2,300
Income from operations				2,000
Net income				$ 1,300