Income Taxes, Tax Credits and Loss Carryforwards (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
U.S. state [Member]
Operating Loss Carryforwards
NOLs (gross amount)	$ 10,039
U.S. foreign [Member]
Operating Loss Carryforwards
Income tax credits	$ 575
Income tax credits, expiration	Dec. 31, 2027
U S State Income Tax Credits Limited [Member] | U.S. state [Member]
Operating Loss Carryforwards
Income tax credits	$ 80
U S State Income Tax Credits Unlimited [Member] | U.S. state [Member]
Operating Loss Carryforwards
Income tax credits	$ 6
Minimum [Member] | U.S. state [Member]
Operating Loss Carryforwards
NOLs, expiration	Dec. 31, 2019
Minimum [Member] | U S State Income Tax Credits Limited [Member] | U.S. state [Member]
Operating Loss Carryforwards
Income tax credits, expiration	Dec. 31, 2019
Maximum [Member] | U.S. state [Member]
Operating Loss Carryforwards
NOLs, expiration	Dec. 31, 2038
Maximum [Member] | U S State Income Tax Credits Limited [Member] | U.S. state [Member]
Operating Loss Carryforwards
Income tax credits, expiration	Dec. 31, 2031