Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Net tax benefit related to reduction in U.S. corporate tax rate	$ 8,400,000
One-time tax expense resulting from transition tax	$ 10,600,000
Statutory federal rate	35.00%	35.00%	35.00%
Increase in valuation allowance	$ 636,000	$ 1,800,000	$ 378,000
U.S federal net operating loss carryforwards	$ 67,900,000	76,400,000
Period to utilize the net operating loss carryforwards	18 years
NOL carryforward used in period	$ 9,100,000	6,200,000
Foreign operating loss carryforwards	5,400,000	3,000,000
Foreign operating loss carryforward, no expiration	4,900,000
Foreign operating loss carryforward, expiring	526,000
Unrecognized tax benefits including interest and penalties	3,100,000	2,800,000
Unrecognized tax benefits that would impact effective rate	2,700,000	2,800,000
Reduction of uncertain tax benefits related to certain liabilities for unrecognized tax benefits	307,000
Reduction in transition tax under TCJA, if realized	307,000
Reduction in valuation allowance		2,300,000
Accrued interest and penalties	304,000	216,000
Income tax penalties and interest expense	88,000	$ 30,000	$ 6,000
Maximum
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Estimated change in unrecognized tax benefit in next twelve months, lower bound	$ (500,000)