Unaudited Interim Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Total Equity	Cumulative effect of adoption of accounting changes Retained Earnings		Cumulative effect of adoption of accounting changes Total Equity
Beginning Balance at Dec. 31, 2018		$ 2,500	$ 1,146,592	$ 1,612,435	$ (28,296)	$ 2,733,231	$ (1,114)	[1]	$ (1,114)	[1]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Contributed (distributed) capital-parent/child asset transfers			(4)			(4)
Contributed capital			0			0
Comprehensive income (loss):
Net income (loss)				87,788		87,788
Other comprehensive income (loss), net of tax					132,501	132,501
Total comprehensive income (loss)						220,289
Ending Balance at Mar. 31, 2019		2,500	1,146,588	1,699,109	104,205	2,952,402
Beginning Balance at Dec. 31, 2018		2,500	1,146,592	1,612,435	(28,296)	2,733,231	(1,114)	[1]	(1,114)	[1]
Comprehensive income (loss):
Net income (loss)	$ 136,223
Other comprehensive income (loss), net of tax	278,461
Ending Balance at Jun. 30, 2019		2,500	1,146,588	1,747,544	250,165	3,146,797
Beginning Balance at Mar. 31, 2019		2,500	1,146,588	1,699,109	104,205	2,952,402
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Contributed (distributed) capital-parent/child asset transfers			0			0
Contributed capital			0			0
Comprehensive income (loss):
Net income (loss)	48,435			48,435		48,435
Other comprehensive income (loss), net of tax	145,960				145,960	145,960
Total comprehensive income (loss)						194,395
Ending Balance at Jun. 30, 2019		2,500	1,146,588	1,747,544	250,165	3,146,797
Beginning Balance at Dec. 31, 2019		2,500	1,153,632	1,577,453	281,442	3,015,027	(1,752)	[2]	(1,752)	[2]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Contributed (distributed) capital-parent/child asset transfers			0			0
Comprehensive income (loss):
Net income (loss)				97,612		97,612
Other comprehensive income (loss), net of tax					(126,381)	(126,381)
Total comprehensive income (loss)						(28,769)
Ending Balance at Mar. 31, 2020		2,500	1,153,632	1,673,313	155,061	2,984,506
Beginning Balance at Dec. 31, 2019		2,500	1,153,632	1,577,453	281,442	3,015,027	$ (1,752)	[2]	$ (1,752)	[2]
Comprehensive income (loss):
Net income (loss)	107,144
Other comprehensive income (loss), net of tax	147,035
Ending Balance at Jun. 30, 2020		2,500	1,476,690	1,682,845	428,477	3,590,512
Beginning Balance at Mar. 31, 2020		2,500	1,153,632	1,673,313	155,061	2,984,506
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Contributed (distributed) capital-parent/child asset transfers			(1,942)			(1,942)
Contributed capital			325,000			325,000
Comprehensive income (loss):
Net income (loss)	9,532			9,532		9,532
Other comprehensive income (loss), net of tax	$ 273,416				273,416	273,416
Total comprehensive income (loss)						282,948
Ending Balance at Jun. 30, 2020		$ 2,500	$ 1,476,690	$ 1,682,845	$ 428,477	$ 3,590,512

[1] Includes the impact from the adoption of ASU 2017-08 and 2017-12. See Note 2 to the Consolidated 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.