Goodwill and Other Intangible Assets - Schedule of Future Amortization Expense and Rent Offset (Details) $ in Millions	Sep. 30, 2018 USD ($)
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Remainder of 2018	$ 125
2019	473
2020	418
2021	342
2022	284
Thereafter	1,777
Total	3,419
Rent offset
Remainder of 2018	(1)
2019	(2)
2020	(2)
2021	(2)
2022	(2)
Thereafter	(3)
Total	$ (12)