Benefit Plans - Changes in Projected Benefit Obligations and Fair Value of Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in projected benefit obligation:
Projected benefit obligation as of the beginning of the period	$ 27,539	$ 30,877
Acquired	16,831	0
Service cost	910	548	$ 614
Interest cost	1,794	1,107	1,192
Actuarial (gain) loss	6,688	(2,917)
Benefits paid	(1,620)	(2,076)
Projected benefit obligation as of the end of the period	52,142	27,539	30,877
Changes in fair value of plan assets:
Fair value of plan assets as of the beginning of the period	20,254	23,461
Acquired	16,027	0
Actual return (loss) on plan assets	6,405	(1,131)
Employer contributions	1,800	0
Benefits paid	(1,620)	(2,076)
Fair value of plan assets as of the end of the period	$ 42,866	$ 20,254	$ 23,461