Related Party Transactions (Detail) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended	12 Months Ended		3 Months Ended	0 Months Ended
	Mar. 31, 2015	Dec. 31, 2014		Mar. 31, 2014	Nov. 05, 2014	Aug. 31, 2014
Effective date	August 8, 2014
Management fee percentage						75.00%
Receivable for advisory and service fees, from affiliates	$ 10,268,000	$ 10,402,000	[1]
Maximum
Management fee percentage						120.00%
Chimera
Investments with affiliate, available-for-sale equity securities - shares	45.0	45.0
Investments with affiliate, available-for-sale equity securities - fair value	141,200,000	143,000,000
Investments with affiliate, available-for-sale equity securities - unrealized gains	2,400,000	4,200,000
Advisory fees from affiliate	10,500,000
Receivable for advisory and service fees, from affiliates	10,300,000	10,400,000
Chimera and CreXus
Advisory fees from affiliate				$ 6,100,000
Amendment Agreement
Basis for management fee	Amount equal to 1/12th of 1.05% of stockholders' equity,
Management Agreement, term					2 years
Term of management agreement expiration date					Dec. 31, 2016
Renewal term					2 years
Management agreement, termination, description	At least two-thirds of the Company's independent directors or the holders of a majority of the Company's outstanding shares of common stock elect to terminate the agreement in their sole discretion and for any or no reason.
Amendment Agreement | Minimum
Management agreement, required period to terminate from the date of the notice					1 year

[1] Derived from the audited consolidated financial statements at December 31, 2014.