Revenue Recognition, Accounts Receivable (Details) - USD ($) $ in Millions		Jun. 30, 2018	Dec. 31, 2017
Accounts receivable
Customer and agents		$ 886	$ 861
Other		101	$ 100
Accounts receivable from contract with customer
Accounts receivable
Customer and agents		882
Other		78
Total	[1]	$ 960

[1] These amounts do not include accounts receivable related to revenues outside the scope of ASU 2014-09; therefore, accounts receivable line items presented in this table will not agree to amounts presented in the Consolidated Balance Sheet.