Pension and Other Postretirement Benefit Plans - Assets that are Carried at Fair Value, and the Method Used to Determine Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Long Corporate Bond Fund [Member]
Pooled Separate Accounts
Average duration of bonds	3 months
Retirement Plan [Member]
Pooled Separate Accounts
Plan Investments	$ 26,059	$ 27,720	$ 25,505
Retirement Plan [Member] | Long Duration Bond Fund [Member]
Pooled Separate Accounts
Plan Investments	11,700	12,229
Retirement Plan [Member] | Long Corporate Bond Fund [Member]
Pooled Separate Accounts
Plan Investments	5,157	5,587
Retirement Plan [Member] | Prudential Short-term [Member]
Pooled Separate Accounts
Plan Investments	150	286
Retirement Plan [Member] | Investment Grade Bond Fund [Member]
Pooled Separate Accounts
Plan Investments	$ 9,052	$ 9,618