Organization (Details)	6 Months Ended
Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Required Annual Distribution of Taxable Net Income	90.00%
Intended annual distribution of taxable net income	100.00%

Intended Annual Distribution of Taxable Net Income

No definition available.

Name:	agnc_IntendedAnnualDistributionofTaxableNetIncome
Namespace Prefix:	agnc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration