Revenue Recognition Details 1 (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Rollforward of Customer Pre-payments and Other Deferred Revenue [Line Items]
Cumulative Effect on Retained Earnings, before Tax	$ 0
Unbilled Contracts Receivable	16,000,000
Deferred Revenue and Credits, Current	130,704,000	$ 107,166,000
Customer pre-payments/deferred revenue	151,009,000
Contract with Customer, Liability, Revenue Recognized	(129,796,000)
Temporary Equity, Foreign Currency Translation Adjustments	$ 2,325,000
Revenue, Practical Expedient, Remaining Performance Obligation [true/false]	true
Customer Pre-payments [Member]
Rollforward of Customer Pre-payments and Other Deferred Revenue [Line Items]
Customer Advances and Deposits, Current	$ 58,898,000	56,772,000
Customer pre-payments/deferred revenue	96,878,000
Contract with Customer, Liability, Revenue Recognized	(95,913,000)
Temporary Equity, Foreign Currency Translation Adjustments	1,161,000
Other Deferred Revenue [Member]
Rollforward of Customer Pre-payments and Other Deferred Revenue [Line Items]
Deferred Revenue	71,806,000	$ 50,394,000
Customer pre-payments/deferred revenue	54,131,000
Contract with Customer, Liability, Revenue Recognized	(33,883,000)
Temporary Equity, Foreign Currency Translation Adjustments	$ 1,164,000