Income Taxes - Effective Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Components of income before income taxes
Domestic income	$ 10,997	$ 9,663	$ 6,764
Foreign income	17,375	13,118	6,222
Income before income taxes	28,372	22,781	12,986
Composition of income tax expense
Current income tax expense	15,800	11,880	4,693
Deferred income tax (benefit)	(5,428)	(2,838)	(2,264)
Income tax expense	10,372	9,042	2,429
Foreign withholding tax included in current tax expense	$ 1,700	$ 1,500	$ 1,100
Effective tax rates reconciliation
Pre-tax book income - US Only (as a percent)	35.00%	35.00%	35.00%
Permanent items (as a percent)	3.20%	4.00%	3.20%
Return to provision true-ups - Current/Deferred (as percent)	(1.10%)	(1.40%)	(3.80%)
Foreign rate differential (as a percent)	2.40%	2.20%	3.40%
Foreign tax credits (as a percent)	(32.00%)	(24.50%)	(31.10%)
Change in valuation allowance (as a percent)	0.00%	0.00%	(19.60%)
Foreign withholding taxes (as a percent)	6.00%	6.70%	8.90%
Deferred foreign tax credit offset (as a percent)	0.00%	(2.20%)	4.00%
State taxes and state rate change (as a percent)	1.40%	(0.30%)	1.90%
UTP adjustment	0.30%	0.00%	0.00%
Effective tax rate (as a percent)	36.60%	39.70%	18.80%
PUERTO RICO
Effective tax rates reconciliation
Pre-tax book income - PR Only (as a percent)	21.40%	20.20%	16.90%