Goodwill and Other Intangible Assets Future Amortization Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Continuing Operations [Member]
Finite-Lived Intangible Assets [Line Items]
Pre-tax amortization expense, remainder of 2018	$ 618		$ 618
Pre-tax amortization expense, 2019	1,254		1,254
Pre-tax amortization expense, 2020	1,244		1,244
Pre-tax amortization expense, 2021	1,228		1,228
Pre-tax amortization expense, 2022	1,221		1,221
Pre-tax amortization expense, 2023	1,207		1,207
Successor [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense	$ 333		$ 648
Predecessor [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense		$ 57		$ 108