Revenue Recognition Details Textual (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Contract liabilities	$ 140,000	$ 133,300	$ 132,400
Contract with Customer, Liability, Revenue Recognized	$ 115,000	$ 117,900
Percentage of Revenue related to Long-term contract	69.00%	66.60%
Air and Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue, Remaining Performance Obligation	$ 832,200
Contract with Customer, Liability, Revenue Recognized	$ 1,473,729	$ 1,362,902	$ 1,385,261