Business Acquisition (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	May 18, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 6,024,000	$ 63,934,000	$ 63,934,000		$ 72,365,000
Kay Flow Industries, Inc.
Business Acquisition [Line Items]
Cash				$ 880,000
Accounts receivable				14,699,000
Inventory				25,094,000
Other assets				6,155,000
Intangibles				53,091,000
Goodwill				47,735,000
Property, plant and equipment				27,478,000
Accounts payable				(12,131,000)
Other current liabilities				(4,866,000)
Other liabilities				(28,706,000)
Total purchase price	$ 0			$ 129,429,000