Income taxes - Components of Net Deferred Tax Liability (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Depreciation and amortization	$ 2,136	$ 2,060
Pension obligation	282	300
Renewable energy investment	268	295
Equity investments	63	65
Lease financings	42	130
Securities valuation	1
Securities valuation		(15)
Credit losses on loans	(46)	(54)
Reserves not deducted for tax	(120)	(143)
Employee benefits	(257)	(266)
Other assets	(43)	(65)
Other liabilities	229	189
U.S. foreign tax credits	(39)	0
Valuation allowance	39	0
Net deferred tax liability	$ 2,555	$ 2,496

Deferred Tax Liabilities, Depreciation and Amortization

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Deferred Tax Liabilities, Pension Obligation

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from loss reserves other than estimated credit losses.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from the provision for loan losses.

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