Goodwill (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2018 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Highest goodwill balance among other reporting units			$ 5,675
Average goodwill balance among other reporting units			$ 848
Number of reporting units with allocated goodwill balances			223
Goodwill [Roll Forward]
Balance, beginning of period	$ 199,314	$ 194,674
Acquired goodwill	334	3,068
Goodwill, Translation Adjustments	(1,297)	1,572
Balance, end of period	198,351	199,314
Accumulated goodwill impairment losses	(9,879)	(9,879)
Goodwill impairment	0	0
Accumulated goodwill impairment losses	(9,879)	(9,879)
Goodwill	$ 188,472	$ 189,435