CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net Income (Loss) Attributable to Parent	$ 260,849	$ 182,717	$ 210,708
Other comprehensive income (loss):
Net unrealized gain (loss) from pension and postretirement plans, net of tax	59,005	(2,288)	(6,947)
Other comprehensive income (loss)	59,005	(2,288)	(6,947)
Comprehensive income (loss)	319,854	180,429	203,761
Subsidiaries [Member]
Net Income (Loss) Attributable to Parent	336,063	274,280	292,924
Other comprehensive income (loss):
Net unrealized gain (loss) from pension and postretirement plans, net of tax	67,431	7,136	2,022
Amortization of treasury interest rate swaps to earnings, net of tax	384	385	385
Other comprehensive income (loss)	67,815	7,521	2,407
Comprehensive income (loss)	$ 403,878	$ 281,801	$ 295,331