CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDER'S EQUITY - USD ($) $ in Thousands	Total	Common Stock	Capital Stock Expense	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance at Dec. 31, 2018	$ 1,819,745	$ 1,346,539	$ (6,357)	$ 484,277	$ (4,714)
Increase (Decrease) in Stockholder's Equity [Roll Forward]
Net Income	186,515			186,515
Other Comprehensive Income (Loss), Net of Tax	(3,057)				(3,057)
Dividends Declared to Parent	(75,000)			(75,000)
Contribution from Parent	50,000	50,000
Ending Balances at Dec. 31, 2019	1,978,203	1,396,539	(6,357)	595,792	(7,771)
Increase (Decrease) in Stockholder's Equity [Roll Forward]
Net Income	191,405			191,405
Other Comprehensive Income (Loss), Net of Tax	(3,171)				(3,171)
Dividends Declared to Parent	(75,000)			(75,000)
Contribution from Parent	250,000	250,000
Ending Balances at Dec. 31, 2020	2,341,437	1,646,539	(6,357)	712,197	(10,942)
Increase (Decrease) in Stockholder's Equity [Roll Forward]
Net Income	201,245			201,245
Other Comprehensive Income (Loss), Net of Tax	1,027				1,027
Dividends Declared to Parent	(62,500)			(62,500)
Contribution from Parent	50,000	50,000
Ending Balances at Dec. 31, 2021	$ 2,531,209	$ 1,696,539	$ (6,357)	$ 850,942	$ (9,915)