Goodwill and Other Intangible Assets Future Amortization Expense (Details) - USD ($) $ in Millions	1 Months Ended	2 Months Ended	3 Months Ended	8 Months Ended	9 Months Ended
	Sep. 30, 2017	Aug. 31, 2017	Sep. 30, 2018	Aug. 31, 2017	Sep. 30, 2018
Continuing Operations [Member]
Finite-Lived Intangible Assets [Line Items]
Pre-tax amortization expense, remainder of 2018			$ 311		$ 311
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	$ 89		$ 307		$ 955
Predecessor [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization expense		$ 31		$ 139