Organization (Details)	3 Months Ended
Mar. 31, 2014
Organization [Abstract]
Required distribution of taxable net income on a annual basis	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