Discontinued Operations (Assets and Liabilities) (Details) - DMT - Disposed of by Sale - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Accounts receivable, net	$ 69,924	$ 97,402
Inventories	54,808	48,910
Other current assets and prepayments	6,653	3,365
Property, plant and equipment, net	3,185	5,541
Rental property and equipment, net	1,041	1,786
Goodwill	176,501	177,799
Other assets	1,244	45
Total assets of discontinued operations	313,356	334,848
Accounts payable and accrued liabilities	34,244	36,592
Advance billings	44,694	30,607
Other noncurrent liabilities	5,281	5,609
Total liabilities of discontinued operations	$ 84,219	$ 72,808