Goodwill And Intangible Assets - Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Goodwill, Gross				$ 189,943	$ 161,001	$ 161,075
Accumulated impairment losses				(73,111)	(73,111)	(73,111)
Goodwill, Net, Beginning Balance	$ 116,832	$ 87,890	$ 87,964	$ 116,832	$ 87,890	$ 87,964
Goodwill acquired during the year	29,029
Effects of foreign currency exchange	(87)	(74)
Goodwill, Net, Ending Balance	116,832	87,890	87,964
Impairment of goodwill	$ 0	$ 0	$ 0