Income Taxes - Additional Information (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Federal corporate income tax rate			21.00%	35.00%	35.00%
Deferred tax assets and liabilities income tax rate expected to reverse in future			26.40%
Increase in deferred tax provision for income taxes, including adjustments to valuation allowances			$ 1,000
Increase in valuation allowance	$ 2,200
Increase in cumulative foreign tax credit carry forward	2,200
Increase (decrease) in provision for income tax		$ 1,100
Income taxes provided for additional outside basis difference inherent in entities as result of reinvestment			$ 8,200
Operating loss carryforwards expiration term			20 years
Deferred tax assets, valuation allowance	1,636		$ 5,112	$ 1,636	$ 1,131	$ 933
Valuation allowance, deferred tax asset, increase (decrease), amount			3,476	505	198
Unrecognized tax benefits	820		216	820	$ 1,185	$ 400
Unrecognized tax benefits that would impact effective tax rate	700		200	700
Unrecognized tax benefits, income tax penalties and interest accrued	200		$ 0	200
Earliest Tax Year | Internal Revenue Service (IRS)
Income Taxes [Line Items]
Open tax year			2014
Earliest Tax Year | State and Foreign Jurisdictions
Income Taxes [Line Items]
Open tax year			2014
Latest Tax Year | Internal Revenue Service (IRS)
Income Taxes [Line Items]
Open tax year			2017
Latest Tax Year | State and Foreign Jurisdictions
Income Taxes [Line Items]
Open tax year			2017
Foreign Tax Authority
Income Taxes [Line Items]
Operating loss carryforwards	4,100		$ 3,500	4,100
Deferred tax assets, valuation allowance	1,100		1,100	1,100
Valuation allowance, deferred tax asset, increase (decrease), amount			3,500
Domestic Tax Authority
Income Taxes [Line Items]
Operating loss carryforwards			$ 8,900
Net operating loss carry-forwards, expiration year			2034
State and Local Jurisdiction
Income Taxes [Line Items]
Tax credit carry-forward, amount			$ 2,600
Deferred tax assets, tax credit carry-forwards	$ 1,785		$ 2,041	$ 1,785
State and Local Jurisdiction | Earliest Tax Year
Income Taxes [Line Items]
Tax credit carry-forwards, expiration year			2021
State and Local Jurisdiction | Latest Tax Year
Income Taxes [Line Items]
Tax credit carry-forwards, expiration year			2027