Fair Value Measurements and Derivative Instruments Reporting (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 0		$ 0		$ 0
Operating expenses	36,271,000	$ 30,691,000	101,865,000	$ 90,496,000
Katowice Leashold Improvements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value on a nonrecurring basis	$ 0		$ 0		0
Operating expenses					$ 400,000
BMO Credit Agreement [Member] | Interest Rate Swap Liability [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument maturity date			Aug. 01, 2019