Goodwill and Other Intangible Assets (Schedule of intangible assets and goodwill) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Finite-lived Intangible Assets [Roll Forward]
Finite-Lived Intangible Assets, Gross	$ 77,536	$ 76,697
Accumulated amortization	(29,255)	(23,805)
Net carrying amount	184,287	180,934
Net carrying amount	48,281	52,892
Gross carrying amount	184,287	180,934
Accumulated amortization	0	0
AEC Trademarks and trade names [Member]
Finite-lived Intangible Assets [Roll Forward]
Finite-Lived Intangible Assets, Gross	208	208
Accumulated amortization	(148)	(135)
Net carrying amount	60	73
Net carrying amount	$ 60	$ 73
AEC Trademarks and trade names [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	6 years	6 years
AEC Trademarks and trade names [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	15 years	15 years
AEC Technology [Member]
Finite-lived Intangible Assets [Roll Forward]
Finite-Lived Intangible Assets, Gross	$ 6,522	$ 6,191
Accumulated amortization	(871)	(387)
Net carrying amount	5,651	5,804
Net carrying amount	$ 5,651	$ 5,804
AEC Technology [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	10 years	10 years
AEC Technology [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	15 years	15 years
AEC Intellectual property [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	15 years	15 years
Finite-lived Intangible Assets [Roll Forward]
Finite-Lived Intangible Assets, Gross	$ 1,250	$ 1,250
Accumulated amortization	(68)	(7)
Net carrying amount	1,182	1,243
Net carrying amount	$ 1,182	$ 1,243
AEC Customer contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	6 years	6 years
Finite-lived Intangible Assets [Roll Forward]
Finite-Lived Intangible Assets, Gross	$ 17,471	$ 17,471
Accumulated amortization	(13,110)	(10,927)
Net carrying amount	4,361	6,544
Net carrying amount	4,361	6,544
AEC Customer relationships [Member]
Finite-lived Intangible Assets [Roll Forward]
Finite-Lived Intangible Assets, Gross	51,763	51,255
Accumulated amortization	(14,768)	(12,108)
Net carrying amount	36,995	39,147
Net carrying amount	$ 36,995	$ 39,147
AEC Customer relationships [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	8 years	8 years
AEC Customer relationships [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	15 years	15 years
AEC Other intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets, weighted average useful life	5 years	5 years
Finite-lived Intangible Assets [Roll Forward]
Finite-Lived Intangible Assets, Gross	$ 322	$ 322
Accumulated amortization	(290)	(241)
Net carrying amount	32	81
Net carrying amount	32	81
MC Goodwill [Member]
Finite-lived Intangible Assets [Roll Forward]
Net carrying amount	69,884	67,672
Gross carrying amount	69,884	67,672
Accumulated amortization	0	0
AEC Goodwill [Member]
Finite-lived Intangible Assets [Roll Forward]
Net carrying amount	114,403	113,262
Gross carrying amount	114,403	113,262
Accumulated amortization	$ 0	$ 0