Income Taxes, Tax Credits and Loss Carryforwards (Details) $ in Millions	Dec. 31, 2019 USD ($)
U.S. State [Member]
Operating Loss Carryforwards
NOLs (gross amount)	$ 10,913
U.S. State [Member] | U S State Income Tax Credits (Gross Amount) Limited [Member]
Operating Loss Carryforwards
Income tax credits	89
U.S. State [Member] | U S State Income Tax Credits (Gross Amount) Unlimited [Member]
Operating Loss Carryforwards
Income tax credits	17
U.S. Foreign [Member]
Operating Loss Carryforwards
Income tax credits	$ 598