Nature of Operations and Basis of Presentation - Narrative (Details) - USD ($) $ in Millions			3 Months Ended
	Jan. 01, 2020	Jan. 01, 2019	Mar. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of accounting standards			$ (1,144)
Accounting Standards Update 2016-02 [Member] | Right-of-use Assets [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of accounting standards		$ 1,000
Accounting Standards Update 2016-02 [Member] | Noncancelable Operating Lease Obligations [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of accounting standards		$ 1,000
Forecast [Member] | Minimum [Member] | Accounting Standards Update 2016-13 [Member] | Credit Losses [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of accounting standards	$ 700
Forecast [Member] | Minimum [Member] | Accounting Standards Update 2016-13 [Member] | Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of accounting standards	(500)
Forecast [Member] | Maximum [Member] | Accounting Standards Update 2016-13 [Member] | Credit Losses [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of accounting standards	900
Forecast [Member] | Maximum [Member] | Accounting Standards Update 2016-13 [Member] | Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of accounting standards	$ (700)