Employee Benefit Plans - Pension Plan Cost and Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Accumulated benefit obligation	$ 58,271		$ 67,923
Change in projected benefit obligation
Beginning balance	67,923		68,959
Service cost	0		0
Interest cost	2,031		1,712	$ 1,635
Settlements	(7,199)		(6,271)
Actuarial (gain) loss	(3,717)		4,240
Benefits paid	(767)		(717)
Ending balance	58,271		67,923	68,959
Change in fair value of plan assets
Beginning balance	66,159		65,189
Actual return on plan assets	(6,983)		7,958
Benefits paid	(767)		(717)
Employer contributions	25,000		0
Settlements	(7,199)		(6,271)
Ending balance	76,210	[1]	66,159	$ 65,189
Funded status recognized in the Consolidated Statements of Financial Condition
Noncurrent asset (liability)	17,939
Noncurrent asset (liability)			(1,764)
Amounts recognized in accumulated other comprehensive loss
Prior service cost	0		0
Net loss	29,345		25,495
Net amount recognized	$ 29,345		$ 25,495
Actuarial losses included in accumulated other comprehensive loss as a percent of
Accumulated benefit obligation	50.40%		37.50%
Fair value of plan assets	38.50%		38.50%
Amounts expected to be amortized from accumulated other comprehensive loss into net periodic benefit cost in the next fiscal year
Prior service cost	$ 0		$ 0
Net loss	426		561
Net amount expected to be recognized	$ 426		$ 561
Weighted-average assumptions at the end of the year used to determine the actuarial present value of the projected benefit obligation
Discount rate	4.10%		3.45%

[1] Additional information regarding the fair value of Pension Plan assets as of December 31, 2018 can be found in Note 21, "Fair Value."