Employee Benefits - Obligations and Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Change in benefit obligation:
Service cost	$ 31,660	$ 25,970	$ 18,926
Interest cost	5,694	9,657	10,996
Pension Plan
Change in benefit obligation:
Benefit obligation at beginning of the year	361,147	396,769	302,317
Service cost	31,660	25,970	18,926
Interest cost	5,694	9,657	10,996
Amendments	(1,106)	(133,439)	0
Actuarial (gain) loss	(1,697)	78,095	74,828
Acquisitions	125,854	0	0
Benefits paid	(20,045)	(15,905)	(10,298)
Benefit obligation at end of the year	501,507	361,147	396,769
Change in plan assets:
Fair value of plan assets at beginning of year	449,643	378,879	305,154
Actual return on plan assets	50,879	48,895	60,723
Acquisitions	63,468	0	0
Employer contribution	2,111	37,773	23,300
Benefits paid	(20,045)	(15,904)	(10,298)
Fair value of plan assets at end of year	546,056	449,643	378,879
Overfunded (underfunded) status	44,549	88,496	(17,890)
Reconciliation of funding status:
Past service credit (cost)	120,792	131,482	(25)
Unrecognized net loss	(128,402)	(161,045)	(113,022)
Prepaid benefit cost	52,159	118,059	95,157
Accumulated benefit obligation	501,507	361,147	290,429
Amounts recognized in accumulated other comprehensive income (“AOCI”), net of tax:
Unrecognized past service credit (cost)	86,837	94,522	(18)
Unrecognized net loss	(92,308)	(115,775)	(81,251)
Net amount	$ (5,471)	$ (21,253)	$ (81,269)