Leases: (Lease Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Operating lease cost	$ 248	$ 259	$ 237
Amortization of right-of-use assets	83	54	31
Interest on lease liabilities	1	1	1
Short-term lease cost	59	55	49
Variable lease cost	23	25	31
Total lease cost	$ 414	$ 394	$ 349