Unaudited Interim Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common   Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive   Income (Loss)
Beginning Balance at Dec. 31, 2020	$ 4,047,716	$ 2,500	$ 1,726,690	$ 1,772,398	$ 546,128
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Contributed capital	105,900		105,900
Comprehensive income (loss):
NET INCOME (LOSS)	103,377			103,377
Other comprehensive income (loss), net of tax	(281,676)				(281,676)
Total comprehensive income (loss)	(178,299)
Ending Balance at Mar. 31, 2021	3,975,317	2,500	1,832,590	1,875,775	264,452
Beginning Balance at Dec. 31, 2020	4,047,716	2,500	1,726,690	1,772,398	546,128
Comprehensive income (loss):
NET INCOME (LOSS)	70,283
Other comprehensive income (loss), net of tax	(110,681)
Ending Balance at Jun. 30, 2021	4,079,127	2,500	1,798,499	1,842,681	435,447
Beginning Balance at Mar. 31, 2021	3,975,317	2,500	1,832,590	1,875,775	264,452
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Contributed capital	(34,091)		(34,091)
Comprehensive income (loss):
NET INCOME (LOSS)	(33,094)			(33,094)
Other comprehensive income (loss), net of tax	170,995				170,995
Total comprehensive income (loss)	137,901
Ending Balance at Jun. 30, 2021	4,079,127	2,500	1,798,499	1,842,681	435,447
Beginning Balance at Dec. 31, 2021	5,955,094	2,500	6,042,491	(437,332)	347,435
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Contributed capital	8,160		8,160
Comprehensive income (loss):
NET INCOME (LOSS)	(24,987)			(24,987)
Other comprehensive income (loss), net of tax	(804,210)				(804,210)
Total comprehensive income (loss)	(829,197)
Ending Balance at Mar. 31, 2022	5,134,057	2,500	6,050,651	(462,319)	(456,775)
Beginning Balance at Dec. 31, 2021	5,955,094	2,500	6,042,491	(437,332)	347,435
Comprehensive income (loss):
NET INCOME (LOSS)	330,251
Other comprehensive income (loss), net of tax	(1,519,017)
Ending Balance at Jun. 30, 2022	4,764,178	2,500	6,040,341	(107,081)	(1,171,582)
Beginning Balance at Mar. 31, 2022	5,134,057	2,500	6,050,651	(462,319)	(456,775)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Contributed capital	3,194		3,194
Contributed (distributed) capital-parent/child asset transfers	(13,504)		(13,504)
Comprehensive income (loss):
NET INCOME (LOSS)	355,238			355,238
Other comprehensive income (loss), net of tax	(714,807)				(714,807)
Total comprehensive income (loss)	(359,569)
Ending Balance at Jun. 30, 2022	$ 4,764,178	$ 2,500	$ 6,040,341	$ (107,081)	$ (1,171,582)