Adoption of ASU 2018-12 - Summary of Effect on Previously Reported Consolidated Statements of Stockholders Equity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	$ 8,604	$ 25,934
Net income (loss)	(1,788)	(1,675)	$ 3,297
Other comprehensive income (loss), net of tax	4,128	(15,963)	(3,593)
Balance as of end-of-year	10,507	8,604	25,934
Cumulative effect from adoption of new accounting standards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year			4,822
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	1,414	3,734	4,167
Net income (loss)	(1,788)	(1,675)	3,297
Balance as of end-of-year	(869)	1,414	3,734
Retained Earnings | Cumulative effect from adoption of new accounting standards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year			(1,820)
Accumulated other comprehensive income
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	(5,713)	10,250	9,021
Other comprehensive income (loss), net of tax	4,128	(15,963)	(3,593)
Balance as of end-of-year	(1,585)	(5,713)	10,250
Accumulated other comprehensive income | Cumulative effect from adoption of new accounting standards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year			4,822
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	8,266	22,860
Net income (loss)		(1,285)	2,109
Other comprehensive income (loss), net of tax		(13,617)	(2,477)
Balance as of end-of-year		8,266	22,860
As Previously Reported | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	2,436	4,366	4,167
Net income (loss)		(1,285)	2,109
Balance as of end-of-year		2,436	4,366
As Previously Reported | Accumulated other comprehensive income
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	(7,073)	6,544	9,021
Other comprehensive income (loss), net of tax		(13,617)	(2,477)
Balance as of end-of-year		(7,073)	6,544
Accounting Standards Update 2018-12 | Cumulative effect from adoption of new accounting standards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year			3,002
Accounting Standards Update 2018-12 | Retained Earnings | Cumulative effect from adoption of new accounting standards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year			(1,820)
Accounting Standards Update 2018-12 | Accumulated other comprehensive income | Cumulative effect from adoption of new accounting standards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year			4,822
Accounting Standards Update 2018-12 | Adoption of New Accounting Standard
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	338	3,074
Net income (loss)		(390)	1,188
Other comprehensive income (loss), net of tax		(2,346)	(1,116)
Balance as of end-of-year		338	3,074
Accounting Standards Update 2018-12 | Adoption of New Accounting Standard | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	(1,022)	(632)
Net income (loss)		(390)	1,188
Balance as of end-of-year		(1,022)	(632)
Accounting Standards Update 2018-12 | Adoption of New Accounting Standard | Retained Earnings | Cumulative effect from adoption of new accounting standards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year		(1,820)
Balance as of end-of-year			(1,820)
Accounting Standards Update 2018-12 | Adoption of New Accounting Standard | Accumulated other comprehensive income
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	$ 1,360	3,706
Other comprehensive income (loss), net of tax		(2,346)	(1,116)
Balance as of end-of-year		$ 1,360	3,706
Accounting Standards Update 2018-12 | Adoption of New Accounting Standard | Accumulated other comprehensive income | Cumulative effect from adoption of new accounting standards
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year			$ 4,822