Weighted Average Shares Outstanding and Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Weighted Avg Shares Outstanding and Earnings Per Share [Line Items]
Net Income Attributable to Parent	$ 37,105	$ 30,759	$ 40,047	$ 31,812
Weighted average common shares outstanding, basic	39,599	39,378	39,539	39,317
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	714	519	666	546
Weighted average common shares outstanding, diluted	40,313	39,897	40,205	39,863
Basic (in dollars per share)	$ 0.94	$ 0.78	$ 1.01	$ 0.81
Diluted (in dollars per share)	$ 0.92	$ 0.77	$ 1.00	$ 0.80