Goodwill and Other Intangible Assets (Schedule of intangible assets and goodwill) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Amortized intangible assets:
Gross carrying value	$ 76,949	$ 76,697
Accumulated amortization	(25,626)	(23,805)
Net carrying amount	51,323	52,892
Gross carrying value	179,366	180,934
Accumulated amortization
Net carrying amount	179,366	180,934
AEC Trademarks and Trade Names [Member]
Amortized intangible assets:
Gross carrying value	208	208
Accumulated amortization	(139)	(135)
Net carrying amount	$ 69	$ 73
AEC Trademarks and Trade Names [Member] | Minimum [Member]
Amortized intangible assets:
Weighted average amortization life in years	6 years	6 years
AEC Trademarks and Trade Names [Member] | Maximum [Member]
Amortized intangible assets:
Weighted average amortization life in years	15 years	15 years
AEC Technology [Member]
Amortized intangible assets:
Gross carrying value	$ 6,142	$ 6,191
Accumulated amortization	(537)	(387)
Net carrying amount	$ 5,605	$ 5,804
AEC Technology [Member] | Minimum [Member]
Amortized intangible assets:
Weighted average amortization life in years	10 years	10 years
AEC Technology [Member] | Maximum [Member]
Amortized intangible assets:
Weighted average amortization life in years	15 years	15 years
AEC Intellectual Property [Member]
Amortized intangible assets:
Gross carrying value	$ 1,250	$ 1,250
Accumulated amortization	(28)	(7)
Net carrying amount	$ 1,222	$ 1,243
Weighted average amortization life in years	15 years	15 years
AEC Customer Contracts [Member]
Amortized intangible assets:
Gross carrying value	$ 17,471	$ 17,471
Accumulated amortization	(11,655)	(10,927)
Net carrying amount	$ 5,816	$ 6,544
Weighted average amortization life in years	6 years	6 years
AEC Customer Relationships [Member]
Amortized intangible assets:
Gross carrying value	$ 51,556	$ 51,255
Accumulated amortization	(13,010)	(12,108)
Net carrying amount	$ 38,546	$ 39,147
AEC Customer Relationships [Member] | Minimum [Member]
Amortized intangible assets:
Weighted average amortization life in years	8 years	8 years
AEC Customer Relationships [Member] | Maximum [Member]
Amortized intangible assets:
Weighted average amortization life in years	15 years	15 years
Other Intangible [Member]
Amortized intangible assets:
Gross carrying value	$ 322	$ 322
Accumulated amortization	(257)	(241)
Net carrying amount	$ 65	$ 81
Weighted average amortization life in years	5 years	5 years
MC Goodwill [Member]
Amortized intangible assets:
Gross carrying value	$ 66,679	$ 67,672
Accumulated amortization
Net carrying amount	66,679	67,672
AEC Goodwill [Member]
Amortized intangible assets:
Gross carrying value	112,687	113,262
Accumulated amortization
Net carrying amount	$ 112,687	$ 113,262