Income Taxes - Carryforwards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Abstract]
U.S. foreign tax credits	$ 1,016
U.S. general business credits	364
State net operating losses and tax credits	312
Foreign net operating losses and tax credits	686
Total loss and credit carryforwards	2,378	$ 2,310
DTA Net of Valuation Allowance, U.S. foreign tax credits	17
DTA Net of Valuation Allowance, U.S. general business tax credits	364
DTA Net of Valuation Allowance, State net operating losses and tax credits	32
DTA Net of Valuation Allowance, Foreign net operating losses and tax credits	647
Total DTA, Net of Valuation Allowance, Tax Credits And Operating Loss Carryforwards	$ 1,060
Epiration date of U.S. foreign tax credits	2027
Expiration date of U.S. general business credits	2036-2038
Expiration date of Foreign net operating losses and tax credits	Post 2025