Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Assets and liabilities:
Accounts receivable and inventory allowances	$ 1,044	$ 839
Deferred rent	1,833	1,212
Acquired intangible assets and property and equipment	(35,524)	(56,801)
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals	7,964	7,344
Research and development	1,170	991
Stock option compensation	17,979	14,741
Capital leases	0	(38)
Cumulative Translation Adjustments	40	170
Deferred Tax Assets, Deferred Income	7,471	5,355
Deferred Tax Assets, Derivative Instruments	3	142
Deferred Tax Liabilities, Prepaid Expenses	(15,569)	(13,312)
Deferred Tax Liabilities, Convertible Debt and Capped Call	(7,934)	0
Net operating loss carryforwards	149,848	165,732
Deferred Tax Assets, Gross, Noncurrent	128,325	126,375
Valuation allowance	(19,978)	(23,815)
Deferred tax assets	$ 108,347	$ 102,560