Summary of Significant Accounting Policies Other long-term liabilities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Other long term liabilities [Abstract]
Asset Retirement Obligation, Current	$ 11,000,000	$ 12,000,000
Unrecognized Tax Benefits	37,000,000	40,000,000
Liability, Retirement and Postemployment Benefits	9,000,000	8,000,000
Liability, Pension and Other Postretirement and Postemployment Benefits, Noncurrent	25,000,000	25,000,000
Long-term portion of warranty reserves	6,000,000	11,000,000
Other long term liabilities	37,000,000	38,000,000
Other long-term liabilities	$ 125,000,000	$ 134,000,000