Components of Company's Interest Income and Interest Expense (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Interest income:
Residential Investment Securities		$ 515,910	$ 315,717
Residential mortgage loans		3,864
Commercial investment portfolio	[1]	64,345	70,187
Reverse repurchase agreements		3,608	2,239
Total interest income		587,727	388,143
Interest expense:
Repurchase agreements		173,090	132,891
Securitized debt of consolidated VIEs		14,850	9,033
Participation sold		153	158
Other		10,332	5,365
Total interest expense		198,425	147,447
Net interest income		$ 389,302	$ 240,696

[1] Includes commercial real estate debt, preferred equity and corporate debt.