Goodwill and Other Intangible Assets (Schedule of Finite-Lived Intangible Assets by Major Class) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule of Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying value	$ 159,503	$ 148,395
Accumulated amortization and impairment losses	(102,537)	(93,924)
Other intangible assets, net	56,966	54,471
Licenses
Schedule of Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying value	19,414	10,267
Accumulated amortization and impairment losses	0	0
Other intangible assets, net	19,414	10,267
Customer relationships and customer lists
Schedule of Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying value	97,419	95,458
Accumulated amortization and impairment losses	(60,221)	(51,633)
Other intangible assets, net	37,198	43,825
Value of business acquired
Schedule of Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying value	20,200	20,200
Accumulated amortization and impairment losses	(20,200)	(20,200)
Other intangible assets, net	0	0
Software
Schedule of Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying value	12,230	12,230
Accumulated amortization and impairment losses	(12,230)	(12,230)
Other intangible assets, net	0	0
Patents and intellectual property
Schedule of Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying value	4,500	4,500
Accumulated amortization and impairment losses	(4,500)	(4,500)
Other intangible assets, net	0	0
Covenants not-to-compete
Schedule of Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying value	4,030	4,030
Accumulated amortization and impairment losses	(4,030)	(4,030)
Other intangible assets, net	0	0
Trademarks and trade names
Schedule of Finite and Indefinite-lived Intangible Assets [Line Items]
Gross carrying value	1,710	1,710
Accumulated amortization and impairment losses	(1,356)	(1,331)
Other intangible assets, net	$ 354	$ 379