Accounting Standards Lease accounting standard (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Sep. 30, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total operating lease liabilities		$ 231
ROU asset		$ 226
Cumulative Effect on Retained Earnings, Net of Tax	$ (31)
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax	$ (31)