Equity and Noncontrolling Interests Equity and Noncontrolling Interests - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2016
Equity, Class of Treasury Stock [Line Items]
Deferred tax asset from stock options exercised and restricted stock vestings		$ 179
Stock repurchase program, authorized amount	$ 1,000	1,000
Treasury Stock, Value, Acquired, Cost Method	467	150
Stock Repurchase Program, Remaining Authorized Repurchase Amount	1,600
Post Merger Stock Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount			$ 1,000
Parent
Equity, Class of Treasury Stock [Line Items]
Treasury Stock, Value, Acquired, Cost Method	467	150
Accounting Standards Update 2014-09 [Member]
Equity, Class of Treasury Stock [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax	(45)
Accounting Standards Update 2014-09 [Member] | Parent
Equity, Class of Treasury Stock [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax	(45)	0
Accounting Standards Update 2016-16 [Member]
Equity, Class of Treasury Stock [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax	(546)
Accounting Standards Update 2016-16 [Member] | Parent
Equity, Class of Treasury Stock [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax	$ (546)	$ 0