Income Taxes - Carryforwards (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Interest limitation carry forwards	$ 157	$ 106
R&D and state credit carry forwards	40	$ 29
Federal
Operating Loss Carryforwards [Line Items]
NOL carry forwards	960
Interest limitation carry forwards	614
R&D and state credit carry forwards	40
State
Operating Loss Carryforwards [Line Items]
NOL carry forwards	1,196
Interest limitation carry forwards	317
R&D and state credit carry forwards	2
Foreign
Operating Loss Carryforwards [Line Items]
NOL carry forwards	181
Interest limitation carry forwards	28
R&D and state credit carry forwards	$ 0