Leases (Schedule of Maturity Analysis of Operating and Finance Lease Liabilities) (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019
Operating Lease Liabilities, Payments Due [Abstract]
Maturity of operating lease liabilities, 2020	$ 4
Maturity of operating lease liabilities, 2021	3
Maturity of operating lease liabilities, 2022	2
Maturity of operating lease liabilities, 2023	2
Maturity of operating lease liabilities, 2024	1
Maturity of operating lease liabilities, after 2024	23
Maturity of operating lease liabilities, total undiscounted lease payments	35
Operating lease liabilities, present value adjustment	(12)
Present value of operating lease liabilities	23	$ 19
Finance Lease Liabilities, Payments, Due [Abstract]
Maturity of finance lease liabilities, 2020	8
Maturity of finance lease liabilities, 2021	7
Maturity of finance lease liabilities, 2022	5
Maturity of finance lease liabilities, 2023	4
Maturity of finance lease liabilities, 2024	2
Maturity of finance lease liabilities, after 2024	3
Maturity of finance lease liabilities, total undiscounted lease payments	29
Finance lease liabilities, present value adjustment	(2)
Present value of finance lease liabilities	$ 27