Basis of Presentation and Significant Accounting Policies Supplemental Cash Flow information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Non Cash Exchange of Puerto Rico Bonds		$ 510
Income Taxes Paid	$ 2	1
Cash and cash equivalents	58	22	$ 24
Restricted Cash	31	0	55
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	91	25	81	$ 83
Long-term Debt [Member]
Interest Paid, Including Capitalized Interest, Operating and Investing Activities	31	38
Variable Interest Entity, Primary Beneficiary [Member]
Restricted Cash	$ 2	$ 3	$ 2