Comprehensive income (Tables)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Components of Other Comprehensive Income (Loss) and Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) to Net Income

The following tables display the components of other comprehensive income (loss) and amounts reclassified from accumulated other comprehensive income (loss) to net income:

	Investment			Defined Benefit			Cash Flow Hedges and			Total Amount				Income
(Dollars in millions)	Securities			Plans			Other			Before Tax				Tax			Net
Balance — January 1, 2023	$	(444	)	$	(273	)	$	(349	)	$	(1,066	)		$	276		$	(790	)
Other comprehensive income before reclassifications:
Unrealized holding gains, net		193			—			—			193				(51	)		142
Foreign currency translation adjustment		—			—			5			5				(1	)		4
Unrealized losses on cash flow hedges		—			—			(116	)		(116	)			30			(86	)
Current year benefit plans gains		—			125			—			125				(33	)		92
Total other comprehensive income (loss) before    reclassifications		193			125			(111	)		207				(55	)		152
Amounts reclassified from accumulated other     comprehensive income that (increase) decrease net income:
Net yield adjustment from cash flow hedges    currently in effect		—			—			250			250		(a)		(66	)		184
Amortization of prior service credit		—			(2	)		—			(2	)	(b)		1			(1	)
Amortization of actuarial gains		—			(5	)		—			(5	)	(b)		1			(4	)
Total other comprehensive income (loss)		193			118			139			450				(119	)		331
Balance — December 31, 2023	$	(251	)	$	(155	)	$	(210	)	$	(616	)		$	157		$	(459	)
Balance — January 1, 2022	$	105		$	(360	)	$	84		$	(171	)		$	44		$	(127	)
Other comprehensive income before reclassifications:
Unrealized holding losses, net		(551	)		—			—			(551	)			143			(408	)
Foreign currency translation adjustment		—			—			(8	)		(8	)			2			(6	)
Unrealized losses on cash flow hedges		—			—			(461	)		(461	)			119			(342	)
Current year benefit plans gains		—			71			—			71				(18	)		53
Total other comprehensive income (loss) before    reclassifications		(551	)		71			(469	)		(949	)			246			(703	)
Amounts reclassified from accumulated other     comprehensive income that (increase) decrease net income:
Amortization of unrealized holding    losses on held-to-maturity securities		2			—			—			2		(a)		(1	)		1
Net yield adjustment from cash flow hedges    currently in effect		—			—			36			36		(a)		(9	)		27
Amortization of prior service credit		—			(2	)		—			(2	)	(b)		—			(2	)
Amortization of actuarial losses		—			18			—			18		(b)		(4	)		14
Total other comprehensive income (loss)		(549	)		87			(433	)		(895	)			232			(663	)
Balance — December 31, 2022	$	(444	)	$	(273	)	$	(349	)	$	(1,066	)		$	276		$	(790	)

	Investment			Defined Benefit			Cash Flow Hedges and			Total Amount				Income
(Dollars in millions)	Securities			Plans			Other			Before Tax				Tax			Net
Balance — January 1, 2021	$	196		$	(650	)	$	370		$	(84	)		$	22		$	(62	)
Other comprehensive income before reclassifications:
Unrealized holding losses, net		(95	)		—			—			(95	)			25			(70	)
Foreign currency translation adjustment		—			—			(1	)		(1	)			—			(1	)
Unrealized losses on cash flow hedges		—			—			(32	)		(32	)			8			(24	)
Current year benefit plans gains		—			206			—			206				(54	)		152
Total other comprehensive income (loss) before    reclassifications		(95	)		206			(33	)		78				(21	)		57
Amounts reclassified from accumulated other     comprehensive income that (increase) decrease net income:
Amortization of unrealized holding    losses on held-to-maturity securities		4			—			—			4		(a)		(1	)		3
Net yield adjustment from cash flow hedges    currently in effect		—			—			(253	)		(253	)	(a)		66			(187	)
Amortization of prior service credit		—			(4	)		—			(4	)	(b)		1			(3	)
Amortization of actuarial losses		—			88			—			88		(b)		(23	)		65
Total other comprehensive income (loss)		(91	)		290			(286	)		(87	)			22			(65	)
Balance — December 31, 2021	$	105		$	(360	)	$	84		$	(171	)		$	44		$	(127	)

(a)Included in interest income.

(b)Included in other costs of operations.

Accumulated Other Comprehensive Income (Loss), Net

Accumulated other comprehensive income (loss), net consisted of the following:

(Dollars in millions)	Investment Securities			Defined Benefit Plans			Cash Flow Hedges and Other			Total
Balance at January 1, 2021	$	145		$	(481	)	$	274		$	(62	)
Net gain (loss) during 2021		(67	)		214			(212	)		(65	)
Balance at December 31, 2021		78			(267	)		62			(127	)
Net gain (loss) during 2022		(407	)		65			(321	)		(663	)
Balance at December 31, 2022		(329	)		(202	)		(259	)		(790	)
Net gain during 2023		142			87			102			331
Balance at December 31, 2023	$	(187	)	$	(115	)	$	(157	)	$	(459	)