Equipment held for lease - Summary of operating lease revenues by type (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating Leases Lease Income [Abstract]
Fixed lease revenue	$ 1,047	$ 1,097	$ 3,205	$ 3,289
Variable lease revenue	269	341	700	1,076
Total	$ 1,316	$ 1,438	$ 3,905	$ 4,365