Reconciliation of Benefit Obligations and Plan Assets of U.K. Plan (Parenthetical) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Compensation And Retirement Disclosure [Abstract]
Additional benefit obligations	$ 754	[1]

[1] On October 26, 2018, the High Court of Justice in the U.K. ruled that the Guaranteed Minimum Pensions (“GMPs”) provided by pension schemes need to equalize lifetime GMP benefits between genders. In order to meet the requirements set out by the High Court, the Company recorded an estimate of $0.8 million additional benefit obligations based on the existing plan participants, the date the U.K. Plan was allowed to stop accruing additional benefits, the pension plan rules and the approach taken to equalize the benefits. The additional benefit obligation will be amortized and recognized as part of net periodic pension cost in the consolidated statement of operations over the average remaining life expectancy of the plan participants.