Income Taxes - Components of net deferred tax liability (Details) - USD ($)
$ in Thousands
Dec. 31, 2016
Dec. 31, 2015
Components of Deferred Tax Assets and Liabilities [Abstract]    
Accrued expenses $ 662 $ 608
Allowance for bad debt 1,175 1,176
Payroll accruals 1,818 2,085
Foreign tax credits 9,541 8,834
Net operating loss carryforwards 47,019 35,862
Property and equipment, net 1,830 0
Research and development credits 1,420 1,569
Loan costs and interest 3,441 3,519
Other 1,654 2,017
Total deferred tax assets 68,560 55,670
Valuation allowance (28,211) (8,274)
Deferred tax assets, net of valuation allowance 40,349 47,396
Deferred tax liabilities:    
Prepaid expenses and other (512) (1,033)
Intangible assets (46,785) (60,309)
Property and equipment, net 0 (1,364)
Deferred tax liabilities (47,297) (62,706)
Net deferred tax liabilities $ (6,948) $ (15,310)