Leases - NPC - 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
Total lease costs	$ 848	$ 821	$ 857
Weighted-average remaining lease term (years):
Operating leases	7 years 7 months 6 days	7 years 4 months 24 days	7 years 7 months 6 days
Finance leases	28 years 1 month 6 days	27 years 6 months	28 years 9 months 18 days
Weighted-average discount rate:
Operating leases	4.30%	4.50%	5.20%
Finance leases	8.60%	8.50%	8.60%
NPC
Lessee, Lease, Description [Line Items]
Variable	$ 449	$ 434	$ 434
Operating	2	3	3
Finance lease, amortization	13	12	13
Finance lease, interest expense	28	29	37
Total lease costs	$ 492	$ 478	$ 487
Weighted-average remaining lease term (years):
Operating leases	5 years 8 months 12 days	6 years 6 months	7 years 6 months
Finance leases	28 years 8 months 12 days	28 years 8 months 12 days	30 years 7 months 6 days
Weighted-average discount rate:
Operating leases	4.50%	4.50%	4.50%
Finance leases	8.60%	8.60%	8.70%