Income Taxes Deferred income tax assets (liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets and liabilities [Line Items]
Non-current deferred tax asset	$ 21,935	$ 17,099
Non-current deferred tax asset, gross total [Member]
Deferred tax assets and liabilities [Line Items]
Deferred Tax Assets, State Taxes	(1,708)	(1,647)
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	1,223	3,881
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Other	857	1,432
Noncurrent deferred tax asset - depreciation and amortization	(10,027)	(11,735)
Noncurrent deferred tax asset - acquired future tax deductions	6,473	5,778
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost	11,089	8,864
Deferred Tax Assets, Unrealized Currency Losses	5,175	5,360
Noncurrent deferred tax asset - tax credits state	6,764	5,887
Deferred Tax Assets, Inventory	1,938	1,633
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Allowance for Doubtful Accounts	151	0
Deferred Tax Assets, Valuation Allowance, Noncurrent	0	2,354
Noncurrent deferred tax liability [Member]
Deferred tax assets and liabilities [Line Items]
Noncurrent deferred tax liability - foreign	1,370	1,372
Deferred Tax Liabilities, Net	$ 1,370	$ 1,372