The cumulative amount of the reporting entity's undistributed earnings or deficit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(30)(a)(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(23)(a)(4))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Name:	us-gaap_RetainedEarningsAccumulatedDeficit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

MORTGAGE BANKING - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Retained earnings	$ 6,011		$ 6,498
Loans and leases	127,528		119,088
Mortgage loans serviced for others \| Banking Subsidiaries
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 79,200		$ 77,500
Cumulative Effect, Period Of Adoption, Adjustment \| Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Retained earnings		$ 6