Leases - PAC - Schedule of Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Variable	$ 611	$ 592	$ 623
Operating	161	151	170
Finance lease, amortization	23	18	16
Finance lease, interest expense	38	40	41
Short-term	15	20	7
Total lease costs	$ 848	$ 821	$ 857
Weighted-average remaining lease term (years):
Finance leases	28 years 1 month 6 days	27 years 6 months	28 years 9 months 18 days
Operating leases	4.30%	4.50%	5.20%
Weighted-average discount rate:
Finance leases	8.60%	8.50%	8.60%
Operating leases	7 years 7 months 6 days	7 years 4 months 24 days	7 years 7 months 6 days
PAC
Lessee, Lease, Description [Line Items]
Variable	$ 56	$ 60	$ 77
Operating	3	3	3
Finance lease, amortization	5	2	1
Finance lease, interest expense	2	2	2
Short-term	3	1	2
Total lease costs	$ 69	$ 68	$ 85
Weighted-average remaining lease term (years):
Finance leases	10 years 1 month 6 days	8 years 4 months 24 days	9 years 1 month 6 days
Operating leases	3.70%	3.80%	3.70%
Weighted-average discount rate:
Finance leases	11.10%	10.50%	10.60%
Operating leases	12 years 8 months 12 days	13 years 10 months 24 days	14 years