Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets
Employee benefits	$ 208	$ 238
Accrued expenses	86	76
Net operating loss, capital loss and tax credit carryforwards	1,519	1,526
Derivative instruments and interest rate and currency swaps	15	9
Debt fair value adjustment	29	33
Investments	0	177
Valuation allowances	(155)	(178)
Total deferred tax assets	1,702	1,881
Deferred tax liabilities
Property, plant and equipment	385	270
Investments	418	0
Other	42	45
Total deferred tax liabilities	845	315
Net deferred tax assets	$ 857	$ 1,566