Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Components of the plans' funded status reflected in the Consolidated Statements of Financial Position

Change in projected benefit obligation, plan assets and funded status
	As of December 31,
	Pension benefits				Postretirement benefits
($ in millions)	2020		2019		2020		2019
Change in projected benefit obligation
Benefit obligation, beginning of year	$	7,139	$	6,224	$	397	$	375
Service cost	104		117		4		8
Interest cost	210		240		11		14
Participant contributions	—		—		14		15
Actuarial losses (gains)	813		927		22		19
Benefits paid	(522)		(356)		(37)		(39)
Plan amendments	—		—		(102)		—
Translation adjustment and other	(1)		(13)		(1)		5
Curtailment losses (gains)	20		—		10		—
Benefit obligation, end of year	$	7,763	$	7,139	$	318	$	397
Change in plan assets
Fair value of plan assets, beginning of year	$	6,192	$	5,299
Actual return on plan assets	1,300		1,235
Employer contribution	18		27
Benefits paid	(522)		(356)
Translation adjustment and other	(1)		(13)
Fair value of plan assets, end of year	$	6,987	$	6,192
Funded status (1)	$	(776)	$	(947)	$	(318)	$	(397)
Amounts recognized in AOCI
Unamortized pension and other postretirement prior service credit	$	(78)	$	(142)	$	(89)	$	(13)

(1)The funded status is recorded within other liabilities and accrued expenses on the Consolidated Statements of Financial Position.

Change during the period in items not yet recognized as a component of net periodic cost

Changes in items not yet recognized as a component of net cost for pension and other postretirement plans
($ in millions)	Pension benefits		Postretirement benefits
Items not yet recognized as a component of net cost – December 31, 2019	$	(142)	$	(13)
Prior service credit arising during the period	—		(102)
Prior service credit recognized during the period due to curtailment	10		18
Prior service credit amortized to net cost	54		10
Translation adjustment and other	—		(2)
Items not yet recognized as a component of net cost – December 31, 2020	$	(78)	$	(89)

Components of net periodic cost

Components of net cost (benefit) for pension and other postretirement plans
	For the years ended December 31,
	Pension benefits						Postretirement benefits						Total Pension and Postretirement Benefits
($ in millions)	2020		2019		2018		2020		2019		2018		2020		2019		2018
Service cost	$	104	$	117	$	110	$	4	$	8	$	7	$	108	$	125	$	117
Interest cost	210		240		255		11		14		15		221		254		270
Expected return on plan assets	(414)		(403)		(427)		—		—		—		(414)		(403)		(427)
Amortization of prior service credit	(54)		(56)		(56)		(10)		(3)		(21)		(64)		(59)		(77)
Curtailment losses (gains)	10		—		—		(8)		—		—		2		—		—
Costs and expenses	(144)		(102)		(118)		(3)		19		1		(147)		(83)		(117)
Remeasurement of projected benefit obligation	813		927		(255)		22		19		(4)		835		946		(259)
Remeasurement of plan assets	(886)		(832)		727		—		—		—		(886)		(832)		727
Remeasurement (gains) losses	(73)		95		472		22		19		(4)		(51)		114		468
Total net (benefit) cost	$	(217)	$	(7)	$	354	$	19	$	38	$	(3)	$	(198)	$	31	$	351

Weighted average assumptions used to determine for pension plans and postretirement benefits plans the net benefit cost and benefit obligation

Weighted average assumptions used to determine net pension cost and net postretirement benefit cost
	For the years ended December 31,
	Pension benefits						Postretirement benefits
	2020		2019		2018		2020		2019		2018
Discount rate	3.00	%	3.70	%	4.06	%	2.99	%	3.61	%	3.95	%
Expected long-term rate of return on plan assets	7.08		7.34		7.33		n/a		n/a		n/a

Weighted average assumptions used to determine benefit obligations
	For the years ended December 31,
	Pension benefits				Postretirement benefits
	2020		2019		2020		2019
Discount rate	2.51	%	3.31	%	2.39	%	3.27	%

Pension plans' weighted average target asset allocation and the actual percentage of plan assets

Weighted average target asset allocation and actual percentage of plan assets by asset category
	As of December 31, 2020
	Target asset allocation (1)	Actual percentage of plan assets
Pension plan’s asset category	2020	2020		2019
Equity securities (2)	43 - 62%	50	%	50	%
Fixed income securities	33 - 45	38		38
Limited partnership interests	— - 15	10		10
Short-term investments and other	—	2		2
Total without securities lending (3)		100	%	100	%

(1)The target asset allocation considers risk-based exposure while the actual percentage of plan assets utilizes a financial reporting view excluding exposure provided through derivatives.

(2)The actual percentage of plan assets for equity securities includes zero and 1% of private equity investments in 2020 and 2019, respectively, that are subject to the limited partnership interests target allocation and 1% and zero of fixed income mutual funds in 2020 and 2019, respectively, that are subject to the fixed income securities target allocation.

(3)Securities lending collateral reinvestment of $101 million and $258 million is excluded from the table above in 2020 and 2019, respectively.

Fair values of pension plan assets

Fair values of pension plan assets as of December 31, 2020
($ in millions)	Quoted prices in active markets for identical assets (Level 1)			Significant other observable inputs (Level 2)			Significant unobservable inputs (Level 3)			Balance as of December 31, 2020
Equity securities	$	227		$	42		$	—		$	269
Fixed income securities:
U.S. government and agencies	32			865			—			897
Corporate	—			1,709			2			1,711
Short-term investments	210			35			—			245
Free-standing derivatives:
Assets	—			21			—			21
Liabilities	(2)			(21)			—			(23)
Other assets	2			—			—			2
Total plan assets at fair value	$	469		$	2,651		$	2		3,122
% of total plan assets at fair value	15.0		%	84.9		%	0.1		%	100.0		%
Investments measured using the net asset value practical expedient										3,908
Securities lending obligation (1)										(101)
Derivatives counterparty and cash collateral netting										(19)
Other net plan assets (2)										77
Total reported plan assets										$	6,987

(1)The securities lending obligation represents the plan’s obligation to return securities lending collateral received under a securities lending program. The terms of the program allow both the plan and the counterparty the right and ability to redeem/return the securities loaned on short notice. Due to its relatively short-term nature, the outstanding balance of the obligation approximates fair value.

(2)Other net plan assets represent cash and cash equivalents, interest and dividends receivable and net receivables related to settlements of investment transactions, such as purchases and sales.

Fair values of pension plan assets as of December 31, 2019
($ in millions)	Quoted prices in active markets for identical assets (Level 1)			Significant other observable inputs (Level 2)			Significant unobservable inputs (Level 3)			Balance as of December 31, 2019
Equity securities	$	216		$	45		$	—		$	261
Fixed income securities:
U.S. government and agencies	237			1,096			—			1,333
Corporate	—			1,060			—			1,060
Short-term investments	128			252			—			380
Free-standing derivatives:
Assets	—			5			—			5
Liabilities	(2)			(17)			—			(19)
Total plan assets at fair value	$	579		$	2,441		$	—		3,020
% of total plan assets at fair value	19.2		%	80.8		%	—		%	100.0		%
Investments measured using the net asset value practical expedient										3,418
Securities lending obligation										(272)
Derivatives counterparty and cash collateral netting										9
Other net plan assets										17
Total reported plan assets										$	6,192

Rollforward of Level 3 plan assets

Rollforward of Level 3 plan assets during December 31, 2020
			Actual return on plan assets:
($ in millions)	Balance as of December 31, 2019		Relating to assets sold during the period		Relating to assets still held at the reporting date		Purchases, sales and settlements, net		Net transfers in (out) of Level 3		Balance as of December 31, 2020
Fixed income securities:
Corporate	$	—	$	—	$	—	$	2	$	—	$	2
Total Level 3 plan assets	$	—	$	—	$	—	$	2	$	—	$	2

Rollforward of Level 3 plan assets during December 31, 2019
			Actual return on plan assets:
($ in millions)	Balance as of December 31, 2018		Relating to assets sold during the period		Relating to assets still held at the reporting date		Purchases, sales and settlements, net		Net transfers in (out) of Level 3		Balance as of December 31, 2019
Fixed income securities:
Corporate	$	5	$	—	$	—	$	(5)	$	—	$	—
Total Level 3 plan assets	$	5	$	—	$	—	$	(5)	$	—	$	—

Rollforward of Level 3 plan assets during December 31, 2018
			Actual return on plan assets:
($ in millions)	Balance as of December 31, 2017		Relating to assets sold during the period		Relating to assets still held at the reporting date		Purchases, sales and settlements, net		Net transfers in (out) of Level 3		Balance as of December 31, 2018
Equity securities	$	29	$	—	$	3	$	—	$	(32)	$	—
Fixed income securities:
Corporate	10		—		—		(5)		—		5
Total Level 3 plan assets	$	39	$	—	$	3	$	(5)	$	(32)	$	5

Estimated future benefit payments expected to be paid

Estimated future benefit payments expected to be paid in the next 10 years
	As of December 31, 2020
($ in millions)	Pension benefits		Postretirement benefits
2021	$	710	$	25
2022	741		27
2023	733		27
2024	726		27
2025	694		26
2026-2030	2,320		98
Total benefit payments	$	5,924	$	230