Financial Information by Segment & Geographic Area - Narrative (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment									2
Number of reporting segments | segment									2
Revenue, Major Customer [Line Items]
Revenues | $	$ 322,428	$ 370,195	$ 399,016	$ 384,714	$ 385,964	$ 393,954	$ 391,586	$ 406,699	$ 1,476,353	$ 1,578,203	$ 1,328,297
Revenue generated | Customer Concentration Risk | Customer A | Rubber
Revenue, Major Customer [Line Items]
Revenues | $									$ 195,600	$ 201,700	$ 144,400