Segment Information - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
U.S.
Segment Reporting Information [Line Items]
Long-Lived Assets	$ 3,200	$ 2,600	$ 2,200
Non-US [Member]
Segment Reporting Information [Line Items]
Long-Lived Assets	$ 620	$ 520	$ 430

Long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e9038-108599

Name:	us-gaap_NoncurrentAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant