RESIDENTIAL MORTGAGE INVESTMENTS - Additional Information (Detail) (USD $) In Billions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Schedule Of Residential Mortgage Investments [Line Items]
Mortgage securities weighted average contractual maturity, months	288 months
Current-Reset ARMs [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Investments held, basis amount	$ 7.55
Agency securities average months to roll, months	5 months 27 days
Current-Reset ARMs [Member] | Maximum [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Agency securities months to roll	18 months
Longer-To-Reset ARMs [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Investments held, basis amount	$ 5.73
Agency securities average months to roll, months	38 months 27 days
Longer-To-Reset ARMs [Member] | Minimum [Member]
Schedule Of Residential Mortgage Investments [Line Items]
Agency securities months to roll	18 months