Equipment held for lease - Summary of fixed and variable operating lease revenues (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating Leases Lease Income [Abstract]
Fixed lease revenue	$ 1,151	$ 1,047	$ 3,318	$ 3,205
Variable lease revenue	414	269	1,018	700
Total	$ 1,565	$ 1,316	$ 4,336	$ 3,905