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	$ 5,102	$ 19,915
Net income (loss)	(752)	1,358	$ 3,778
Other comprehensive income (loss), net of tax	2,876	(16,336)	(3,574)
Balance as of end-of-year	6,893	5,102	19,915
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	5,924	5,196	8,686
Net income (loss)	(752)	1,358	3,778
Balance as of end-of-year	4,778	5,924	5,196
Retained Earnings | Cumulative Effect to Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year			(6,273)
Accumulated Other Comprehensive Income (Loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	(6,352)	9,984	8,931
Other comprehensive income (loss), net of tax	2,876	(16,336)	(3,574)
Balance as of end-of-year	(3,476)	(6,352)	9,984
Accumulated Other Comprehensive Income (Loss) | Cumulative Effect to Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year			4,627
Accounting Standards Update 2018-12 | Cumulative Effect to Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year			(1,646)
Accounting Standards Update 2018-12 | Retained Earnings | Cumulative Effect to Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year			(6,273)
Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss) | Cumulative Effect to Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year			4,627
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	4,569	20,754
Net income (loss)		(2,241)	1,887
Other comprehensive income (loss), net of tax		(14,109)	(2,490)
Balance as of end-of-year		4,569	20,754
As Previously Reported | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	6,707	9,578	8,686
Net income (loss)		(2,241)	1,887
Balance as of end-of-year		6,707	9,578
As Previously Reported | Accumulated Other Comprehensive Income (Loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	(7,668)	6,441	8,931
Other comprehensive income (loss), net of tax		(14,109)	(2,490)
Balance as of end-of-year		(7,668)	6,441
Adoption of New Accounting Standard | Accounting Standards Update 2018-12
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	533	(839)
Net income (loss)		3,599	1,891
Other comprehensive income (loss), net of tax		(2,227)	(1,084)
Balance as of end-of-year		533	(839)
Adoption of New Accounting Standard | Accounting Standards Update 2018-12 | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	(783)	(4,382)
Net income (loss)		3,599	1,891
Balance as of end-of-year		(783)	(4,382)
Adoption of New Accounting Standard | Accounting Standards Update 2018-12 | Retained Earnings | Cumulative Effect to Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year			(6,273)
Adoption of New Accounting Standard | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year	$ 1,316	3,543
Other comprehensive income (loss), net of tax		(2,227)	(1,084)
Balance as of end-of-year		$ 1,316	3,543
Adoption of New Accounting Standard | Accounting Standards Update 2018-12 | Accumulated Other Comprehensive Income (Loss) | Cumulative Effect to Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Balance as of beginning-of-year			$ 4,627