Commitments and Other Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Operating Leases of Lessee Disclosure

Future minimum commitments under noncancellable operating leases are as follows (dollars in millions):

2018	$	176
2019	112
2020	69
2021	52
2022	32
Thereafter	192
	$	633