Employee Benefit Plans - Components of Net Periodic Benefit Income for the Pension Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Retirement Benefits [Abstract]
Service cost	$ 3,043	$ 3,012	$ 9,185	$ 8,919
Interest cost	17,915	20,942	53,783	62,732
Expected return on plan assets	(38,755)	(38,550)	(116,345)	(115,483)
Amortization of prior service cost	172	173	516	519
Amortization of actuarial loss	12,465	11,130	37,430	33,340
Net periodic benefit income	$ (5,160)	$ (3,293)	$ (15,431)	$ (9,973)