Segment Information (Schedule Of Intercompany Sales By Geographic Area) (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Intercompany sales	$ 165,937	$ 156,362	$ 158,111	$ 152,555	$ 183,363	$ 151,574	$ 170,504	$ 160,722	$ 187,438	$ 166,944	$ 151,512	$ 147,758	$ 632,965	$ 666,163	$ 653,652
Intercompany Sales [Member]
Intercompany sales													155,451	159,591	144,622
Americas [Member] | Intercompany Sales [Member]
Intercompany sales													71,268	64,589	48,323
Germany [Member] | Intercompany Sales [Member]
Intercompany sales													32,246	40,788	46,956
Other EMEA [Member] | Intercompany Sales [Member]
Intercompany sales													20,248	26,855	29,389
Asia Pacific [Member] | Intercompany Sales [Member]
Intercompany sales													31,689	27,359	19,954
Americas [Member] | Operating Segments [Member]
Intercompany sales													340,885	357,976	333,925
Americas [Member] | Intercompany Sales [Member]
Intercompany sales													64,491	74,360	79,056
Americas [Member] | Americas [Member] | Operating Segments [Member]
Intercompany sales													3,013	3,073	201
Americas [Member] | Germany [Member] | Operating Segments [Member]
Intercompany sales													28,881	36,552	43,841
Americas [Member] | Other EMEA [Member] | Operating Segments [Member]
Intercompany sales													10,958	17,133	20,581
Americas [Member] | Asia Pacific [Member] | Operating Segments [Member]
Intercompany sales													21,639	17,602	14,433
Germany [Member] | Operating Segments [Member]
Intercompany sales													78,979	82,872	87,021
Germany [Member] | Intercompany Sales [Member]
Intercompany sales													8,139	6,344	9,967
Germany [Member] | Americas [Member] | Operating Segments [Member]
Intercompany sales													4,123	70	3,217
Germany [Member] | Other EMEA [Member] | Operating Segments [Member]
Intercompany sales													3,850	6,149	6,742
Germany [Member] | Asia Pacific [Member] | Operating Segments [Member]
Intercompany sales													166	125	8
Other EMEA [Member] | Operating Segments [Member]
Intercompany sales													114,162	117,232	109,066
Other EMEA [Member] | Intercompany Sales [Member]
Intercompany sales													75,447	72,192	50,542
Other EMEA [Member] | Americas [Member] | Operating Segments [Member]
Intercompany sales													61,086	58,419	42,622
Other EMEA [Member] | Germany [Member] | Operating Segments [Member]
Intercompany sales													3,365	4,232	3,115
Other EMEA [Member] | Other EMEA [Member] | Operating Segments [Member]
Intercompany sales													5,071	3,494	2,066
Other EMEA [Member] | Asia Pacific [Member] | Operating Segments [Member]
Intercompany sales													5,925	6,047	2,739
Asia Pacific [Member] | Operating Segments [Member]
Intercompany sales													98,939	108,083	123,640
Asia Pacific [Member] | Intercompany Sales [Member]
Intercompany sales													7,374	6,695	5,057
Asia Pacific [Member] | Americas [Member] | Operating Segments [Member]
Intercompany sales													3,046	3,027	2,283
Asia Pacific [Member] | Germany [Member] | Operating Segments [Member]
Intercompany sales														4
Asia Pacific [Member] | Other EMEA [Member] | Operating Segments [Member]
Intercompany sales													369	79
Asia Pacific [Member] | Asia Pacific [Member] | Operating Segments [Member]
Intercompany sales													$ 3,959	$ 3,585	$ 2,774