Other Revenues and Other Expenses Other Revenues (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Component of Operating Income [Abstract]
Distribution Fees	$ 66	$ 62

Amount of fees from providing distribution services, including but not limited to, marketing and selling fund shares, advertising, printing and mailing of prospectuses and sales literature to investors.

No definition available.

Name:	us-gaap_DistributionFees
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration