Commitments and Contingencies (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Operating Lease Payments

Future minimum operating lease payments are as follows (in millions):

2018 (remaining)	$	115
2019	135
2020	106
2021	78
2022	53
Thereafter	51
Total future minimum operating lease payments	$	538

Operating Leases

Future minimum operating lease payments are as follows (in millions):
2018	$	150
2019	127
2020	98
2021	71
2022	46
Thereafter	44
Total future minimum operating lease payments	$	536