Fair Values (Details of Book Value and Fair Value of Financial Instruments) (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible due 2021 - Bond Hedge	$ 16,678,000	$ 0
Convertible Debt Conversion Feature	20,901,000	0
Cash and cash equivalents	138,427,000	60,055,000	$ 33,472,000	$ 38,931,000
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	138,427,000	60,055,000
Other investments	125,000	160,000
Installment receivables, net of reserves	1,810,000	1,793,000
Long-term debt (including current maturities of long-term debt)	160,094,000	47,120,000
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	138,427,000	60,055,000
Other investments	125,000	160,000
Installment receivables, net of reserves	1,810,000	1,793,000
Long-term debt (including current maturities of long-term debt)	157,902,000	47,369,000
Other Debt Obligations [Member] | Foreign currency forward contracts | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	(20,901,000)	0
Other Debt Obligations [Member] | Foreign currency forward contracts | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	(20,901,000)	0
Other Long-Term Assets [Member] | Foreign currency forward contracts | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	16,678,000	0
Other Long-Term Assets [Member] | Foreign currency forward contracts | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	16,678,000	0
Other Current Assets | Foreign currency forward contracts | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	1,979,000	4,143,000
Other Current Assets | Foreign currency forward contracts | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	1,979,000	4,143,000
Accrued Expenses | Foreign currency forward contracts | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	(1,137,000)	(2,014,000)
Accrued Expenses | Foreign currency forward contracts | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	(1,137,000)	$ (2,014,000)
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Convertible Debt Conversion Feature [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible Debt Conversion Feature	20,901,000
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Convertible Debt Bond Hedge [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Convertible due 2021 - Bond Hedge	$ 16,678,000