Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Commitments and Contingencies - Other (Details) - USD ($) $ in Billions	Oct. 24, 2018	Mar. 31, 2020
Contingencies
Total commitments to purchase and fund mortgage loans		$ 9.4
Garfield Action \| Settled Litigation
Contingencies
Percent of shareholder approval for reorganization of the company (as a percent)	99.80%