Employee Benefit Plans - Net Periodic Pension Cost of Defined Benefit Plan (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Sep. 12, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Employee Benefits and Share-based Compensation, Noncash [Abstract]
Service cost		$ 953	$ 35	$ 1,159	$ 86
Interest cost		16	11	47	32
Amortization of prior service cost		20	21	62	63
Net periodic benefit cost		$ 989	$ 67	$ 1,268	$ 181
Defined benefit plan, prior period expense	$ 850