Netting of Financial Instruments - Summary of Offsetting of Derivative Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Gross amounts of recognized assets	$ 34,732	$ 13,385
Gross amounts offset in the consolidated balance sheet	(16,270)	(3,300)
Net amounts of assets presented in the consolidated balance sheet	18,462	10,085
Net amounts of assets presented in the consolidated balance sheet	(16,270)	(3,300)
CRT Agreements [Member]
Derivative [Line Items]
Gross amounts of recognized assets	0	593
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of assets presented in the consolidated balance sheet	0	593
Forward Purchase Contracts [Member]
Derivative [Line Items]
Gross amounts of recognized assets	20,795	2,444
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of assets presented in the consolidated balance sheet	20,795	2,444
Forward Sales Contracts [Member]
Derivative [Line Items]
Gross amounts of recognized assets	138	2,604
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of assets presented in the consolidated balance sheet	138	2,604
Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Gross amounts of recognized assets	9,372	4,983
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of assets presented in the consolidated balance sheet	9,372	4,983
MBS Put Options [Member]
Derivative [Line Items]
Gross amounts of recognized assets	64	93
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of assets presented in the consolidated balance sheet	64	93
Put Options on Interest Rate Futures [Member]
Derivative [Line Items]
Gross amounts of recognized assets	414	1,512
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of assets presented in the consolidated balance sheet	414	1,512
Call Options on Interest Rate Futures [Member]
Derivative [Line Items]
Gross amounts of recognized assets	3,949	1,156
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of assets presented in the consolidated balance sheet	3,949	1,156
Netting [Member]
Derivative [Line Items]
Gross amounts of recognized assets	0	0
Gross amounts offset in the consolidated balance sheet	(16,270)	(3,300)
Net amounts of assets presented in the consolidated balance sheet	(16,270)	(3,300)
Derivatives Not Subject to Master Netting Arrangements [Member]
Derivative [Line Items]
Gross amounts of recognized assets	9,372	5,576
Gross amounts offset in the consolidated balance sheet	0	0
Net amounts of assets presented in the consolidated balance sheet	9,372	5,576
Derivatives Subject to Master Netting Arrangements [Member]
Derivative [Line Items]
Gross amounts of recognized assets	25,360	7,809
Gross amounts offset in the consolidated balance sheet	(16,270)	(3,300)
Net amounts of assets presented in the consolidated balance sheet	$ 9,090	$ 4,509