Goodwill and Other Intangible Assets (Schedule of intangible assets and goodwill) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Amortized intangible assets:
Gross carrying value	$ 67,752	$ 71,901
Accumulated amortization	10,755	5,447
Net carrying amount	56,997	66,454
Goodwill
Gross carrying value	166,010	160,375
Accumulated amortization
Net carrying amount	166,010	160,375
AEC Trade Names [Member]
Amortized intangible assets:
Gross carrying value	43	43
Accumulated amortization	27	23
Net carrying amount	$ 16	$ 20
Goodwill
Amortization life in years	15 years	15 years
AEC Technology [Member]
Amortized intangible assets:
Gross carrying value	$ 228	$ 228
Accumulated amortization	142	124
Net carrying amount	$ 86	$ 104
Goodwill
Amortization life in years	15 years	15 years
Customer Relationships [Member]
Amortized intangible assets:
Gross carrying value	$ 48,528	$ 49,490
Accumulated amortization	4,956	2,481
Net carrying amount	$ 43,572	$ 47,009
Goodwill
Amortization life in years	15 years	15 years
Customer Contracts [Member]
Amortized intangible assets:
Gross carrying value	$ 18,211	$ 20,420
Accumulated amortization	5,114	2,561
Net carrying amount	$ 13,097	$ 17,859
Goodwill
Amortization life in years	6 years	6 years
Other Intangible [Member]
Amortized intangible assets:
Gross carrying value	$ 742	$ 1,720
Accumulated amortization	516	258
Net carrying amount	$ 226	$ 1,462
Goodwill
Amortization life in years	5 years	5 years
MC Goodwill [Member]
Goodwill
Gross carrying value	$ 70,280	$ 64,645
Accumulated amortization
Net carrying amount	70,280	64,645
AEC Goodwill [Member]
Goodwill
Gross carrying value	95,730	95,730
Accumulated amortization
Net carrying amount	$ 95,730	$ 95,730