Consolidating Financial Statements (Details) - Consolidating Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Consolidating Statement of Comprehensive Income
Net income	$ 873	$ 396	$ 557	$ 796	$ 621	$ 709	$ 524	$ 669	$ 2,622	$ 2,523	$ 2,056
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									2,994	(1,489)	294
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									(4)	(27)	8
Net changes in benefit plan assets and obligations									33	(56)	29
Net changes in unrealized foreign currency translation									117	(247)	191
Other comprehensive income (loss) before income taxes									3,140	(1,819)	522
Income tax expense (benefit)									641	(349)	110
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									2,499	(1,470)	412
Other comprehensive income (loss) of subsidiaries									0	0	0
Other comprehensive income (loss), net of taxes									2,499	(1,470)	412
Comprehensive income									5,121	1,053	2,468
TRV [Member]
Consolidating Statement of Comprehensive Income
Net income									2,622	2,523	2,064
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									4	0	(44)
Net changes in benefit plan assets and obligations									35	(53)	22
Other comprehensive income (loss) before income taxes									39	(53)	(22)
Income tax expense (benefit)									12	(17)	2
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									27	(36)	(24)
Other comprehensive income (loss) of subsidiaries									2,472	(1,434)	436
Other comprehensive income (loss), net of taxes									2,499	(1,470)	412
Comprehensive income									5,121	1,053	2,476
Reportable Legal Entities [Member] | TPC [Member]
Consolidating Statement of Comprehensive Income
Net income									2,212	2,110	1,728
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									2,097	(1,028)	313
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									(2)	(20)	6
Net changes in benefit plan assets and obligations									1	1	(1)
Net changes in unrealized foreign currency translation									53	(144)	83
Other comprehensive income (loss) before income taxes									2,149	(1,191)	401
Income tax expense (benefit)									441	(231)	98
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									1,708	(960)	303
Other comprehensive income (loss) of subsidiaries									0	0	0
Other comprehensive income (loss), net of taxes									1,708	(960)	303
Comprehensive income									3,920	1,150	2,031
Reportable Legal Entities [Member] | Other Subsidiaries [Member]
Consolidating Statement of Comprehensive Income
Net income									577	604	462
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									893	(461)	25
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									(2)	(7)	2
Net changes in benefit plan assets and obligations									(3)	(4)	8
Net changes in unrealized foreign currency translation									64	(103)	108
Other comprehensive income (loss) before income taxes									952	(575)	143
Income tax expense (benefit)									188	(101)	10
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									764	(474)	133
Other comprehensive income (loss) of subsidiaries									0	0	0
Other comprehensive income (loss), net of taxes									764	(474)	133
Comprehensive income									1,341	130	595
Reportable Legal Entities [Member] | TRV [Member]
Consolidating Statement of Comprehensive Income
Net income									2,622	2,523	2,064
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									4	0	(44)
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									0	0	0
Net changes in benefit plan assets and obligations									35	(53)	22
Net changes in unrealized foreign currency translation									0	0	0
Other comprehensive income (loss) before income taxes									39	(53)	(22)
Income tax expense (benefit)									12	(17)	2
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									27	(36)	(24)
Other comprehensive income (loss) of subsidiaries									2,472	(1,434)	436
Other comprehensive income (loss), net of taxes									2,499	(1,470)	412
Comprehensive income									5,121	1,053	2,476
Eliminations [Member]
Consolidating Statement of Comprehensive Income
Net income									(2,789)	(2,714)	(2,198)
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income									0	0	0
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income									0	0	0
Net changes in benefit plan assets and obligations									0	0	0
Net changes in unrealized foreign currency translation									0	0	0
Other comprehensive income (loss) before income taxes									0	0	0
Income tax expense (benefit)									0	0	0
Other comprehensive income (loss), net of taxes, before other comprehensive income (loss) of subsidiaries									0	0	0
Other comprehensive income (loss) of subsidiaries									(2,472)	1,434	(436)
Other comprehensive income (loss), net of taxes									(2,472)	1,434	(436)
Comprehensive income									$ (5,261)	$ (1,280)	$ (2,634)