Unaudited Interim Statements of Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)	Cumulative effect of adoption of accounting changes		Cumulative effect of adoption of accounting changes Retained Earnings (Accumulated Deficit)
Beginning Balance at Dec. 31, 2018	$ 6,741,568	$ 2,500	$ 6,120,436	$ 943,005	$ (324,373)	$ (371)	[1]	$ (371)	[1]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Return of capital	(245,000)		(245,000)
Comprehensive income:
Net income (loss)	(900,024)			(900,024)
Other comprehensive income (loss), net of tax	224,777				224,777
Total comprehensive income (loss)	(675,247)
Ending Balance at Mar. 31, 2019	5,820,950	2,500	5,875,436	42,610	(99,596)
Beginning Balance at Dec. 31, 2018	6,741,568	2,500	6,120,436	943,005	(324,373)	(371)	[1]	(371)	[1]
Comprehensive income:
Net income (loss)	(1,296,306)
Other comprehensive income (loss), net of tax	1,055,836
Ending Balance at Sep. 30, 2019	5,764,227	2,500	5,383,936	(353,672)	731,463
Beginning Balance at Mar. 31, 2019	5,820,950	2,500	5,875,436	42,610	(99,596)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Return of capital	(246,500)		(246,500)
Comprehensive income:
Net income (loss)	(168,770)			(168,770)
Other comprehensive income (loss), net of tax	334,395				334,395
Total comprehensive income (loss)	165,625
Ending Balance at Jun. 30, 2019	5,740,075	2,500	5,628,936	(126,160)	234,799
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Return of capital	(245,000)		(245,000)
Comprehensive income:
Net income (loss)	(227,512)			(227,512)
Other comprehensive income (loss), net of tax	496,664				496,664
Total comprehensive income (loss)	269,152
Ending Balance at Sep. 30, 2019	5,764,227	2,500	5,383,936	(353,672)	731,463
Beginning Balance at Dec. 31, 2019	5,527,355	2,500	5,142,936	(46,693)	428,612	(1,392)	[2]	(1,392)	[2]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Return of capital	(207,000)		(207,000)
Comprehensive income:
Net income (loss)	(820,788)			(820,788)
Other comprehensive income (loss), net of tax	1,010,888				1,010,888
Total comprehensive income (loss)	190,100
Ending Balance at Mar. 31, 2020	5,509,063	2,500	4,935,936	(868,873)	1,439,500
Beginning Balance at Dec. 31, 2019	5,527,355	2,500	5,142,936	(46,693)	428,612	$ (1,392)	[2]	$ (1,392)	[2]
Comprehensive income:
Net income (loss)	(2,759,162)
Other comprehensive income (loss), net of tax	1,232,667
Ending Balance at Sep. 30, 2020	3,427,468	2,500	4,570,936	(2,807,247)	1,661,279
Beginning Balance at Mar. 31, 2020	5,509,063	2,500	4,935,936	(868,873)	1,439,500
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Return of capital	(173,000)		(173,000)
Comprehensive income:
Net income (loss)	(1,756,214)			(1,756,214)
Other comprehensive income (loss), net of tax	195,432				195,432
Total comprehensive income (loss)	(1,560,782)
Ending Balance at Jun. 30, 2020	3,775,281	2,500	4,762,936	(2,625,087)	1,634,932
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Return of capital	(192,000)		(192,000)
Comprehensive income:
Net income (loss)	(182,160)			(182,160)
Other comprehensive income (loss), net of tax	26,347				26,347
Total comprehensive income (loss)	(155,813)
Ending Balance at Sep. 30, 2020	$ 3,427,468	$ 2,500	$ 4,570,936	$ (2,807,247)	$ 1,661,279

[1] Includes the impact from the adoption of ASU 2017-08 and 2017-12. See Note 2 to the Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 for additional information.

[2] Includes the impact from the adoption of ASU 2016-13. See Note 2.