Consolidated Balance Sheets (Parentheticals) - USD ($) shares in Millions, $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security Owned and Pledged as Collateral, Fair Value	$ 68,370	$ 92,547
Preferred Stock, Liquidation Preference, Value	1,538	$ 963
Preferred Stock C, Liquidation Preference, Value	325
Preferred Stock D, Liquidation Preference, Value	$ 235
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	900.0	900.0
Common Stock, Shares, Issued	567.7	540.9
Common Stock, Shares, Outstanding	567.7	540.9
Agency Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security Owned and Pledged as Collateral, Fair Value	$ 64,154	$ 92,608
Credit Risk Transfer Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security Owned and Pledged as Collateral, Fair Value	360	309
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security Owned and Pledged as Collateral, Fair Value	437	0
US Treasury Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security Owned and Pledged as Collateral, Fair Value	3,721	481
Receivable for securities sold [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security Owned and Pledged as Collateral, Fair Value	0	0
Asset Pledged as Collateral [Member] \| US Treasury Securities [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Security Owned and Pledged as Collateral, Fair Value	$ 3,721	$ 97

Value of the difference between preference in liquidation and the par or stated values of the preferred C shares.

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Value of the difference between preference in liquidation and the par or stated values of the preferred D shares.

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Face amount or stated value per share of common stock.

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Value of the difference between preference in liquidation and the par or stated values of the preferred shares.

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Fair value of financial instrument held by the entity for its own account (proprietary securities) for trading or investment purposes that are carried at fair value and pledged to counterparties as collateral for financing transactions.

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