Employee Benefits - Obligation and Funded Status (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Benefits
Reconciliation of benefit obligation
Benefit obligation at beginning of year	$ 271,744	$ 252,374
Service cost	12,082	10,829	$ 7,989
Interest cost	6,911	8,266	8,320
Actuarial loss (gain)	(6,593)	38,920
Adjustment for plan amendment	(408)	(32,175)
Special event plan closure	0	0
Benefit payments	(7,149)	(6,470)
Benefit obligation at end of year	276,587	271,744	252,374
Reconciliation of fair value of plan assets
Fair value of plan assets at beginning of year	248,735	199,466
Actual return on plan assets	37,354	45,739
Employer contributions	5,000	10,000
Benefit payments	(7,149)	(6,470)
Fair value of plan assets at end of year	283,940	248,735	199,466
Funded status at end of year	7,353	(23,009)
Accumulated pension benefit obligation	276,518	271,515
Post-retirement Benefits
Reconciliation of benefit obligation
Benefit obligation at beginning of year	31,666	31,001
Service cost	148	1,728	1,823
Interest cost	72	1,014	1,274
Actuarial loss (gain)	(1,101)	(1,084)
Adjustment for plan amendment		0
Special event plan closure	(28,889)	0
Benefit payments	(936)	(993)
Benefit obligation at end of year	960	31,666	31,001
Reconciliation of fair value of plan assets
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	936	993
Benefit payments	(936)	(993)
Fair value of plan assets at end of year	0	0	$ 0
Funded status at end of year	$ (960)	$ (31,666)