Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Compensation	$ 5,899	$ 9,022
Accrued expenses	3,932	4,647
Foreign tax credits	8,758	8,654
Tax attribute carryforwards	2,321	2,016
Derivatives	1,478	938
Foreign currency	8,965	5,443
Deferred revenue	2,521	2,653
Deferred tax assets	33,874	33,373
Valuation allowance	(6,410)	(4,088)
Net deferred tax assets	27,464	29,285
Deferred tax liabilities:
Property	(94,847)	(91,730)
Intangibles	(14,334)	(12,353)
Deferred tax liabilities	(109,181)	(104,083)
Net deferred tax liability	$ (81,717)	$ (74,798)