Income Taxes - Schedule of Net Operating Loss (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Uncertain tax positions	$ (1,587)	$ (40)	$ (16)
Federal
Operating Loss Carryforwards [Line Items]
NOLs per return	12,813
Uncertain tax positions	(5,526)
Financial NOLs	7,287
Federal | Tax Year 2022
Operating Loss Carryforwards [Line Items]
NOLs per return	1,043
Federal | Tax Year 2023
Operating Loss Carryforwards [Line Items]
NOLs per return	1,440
Federal | Tax Year 2024
Operating Loss Carryforwards [Line Items]
NOLs per return	1,402
Federal | Tax Year 2025
Operating Loss Carryforwards [Line Items]
NOLs per return	1,042
Federal | Tax Year 2026
Operating Loss Carryforwards [Line Items]
NOLs per return	1,525
Federal | Tax Year 2027
Operating Loss Carryforwards [Line Items]
NOLs per return	375
Federal | Tax Year 2028
Operating Loss Carryforwards [Line Items]
NOLs per return	637
Federal | Tax Year 2029
Operating Loss Carryforwards [Line Items]
NOLs per return	645
Federal | Tax Year 2030
Operating Loss Carryforwards [Line Items]
NOLs per return	671
Federal | Tax Year 2031
Operating Loss Carryforwards [Line Items]
NOLs per return	732
Federal | Tax Year 2032
Operating Loss Carryforwards [Line Items]
NOLs per return	348
Federal | Tax Year 2033
Operating Loss Carryforwards [Line Items]
NOLs per return	238
Federal | Tax Year 2037
Operating Loss Carryforwards [Line Items]
NOLs per return	$ 2,715