Offsetting of Financial Assets, Liabilities, and Collateral (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Offsetting Asset and Liabilities [Line Items]
Gross Amounts of Recognized Assets	$ 4,852	[1]	$ 2,972	[1]
Gross Amounts Offset in Consolidated Balance Sheet		[1]		[1]
Net Amounts of Assets Presented in Consolidated Balance Sheet	4,852	[1]	2,972	[1]
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments	(4,596)	[1],[2]	(2,210)	[1],[2]
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Received	(212)	[1],[2]
Net Amount	44	[1]	762	[1]
Gross Amounts of Recognized Liabilities	(915,601)	[1]	(603,001)	[1]
Gross Amounts Offset in Consolidated Balance Sheet		[1]		[1]
Net Amounts of Liabilities Presented in Consolidated Balance Sheet	(915,601)	[1]	(603,001)	[1]
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments	887,500	[1],[2]	554,128	[1],[2]
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Pledged	27,762	[1],[2]	48,873	[1],[2]
Net Amount	(339)	[1]
Interest Rate Swaps
Offsetting Asset and Liabilities [Line Items]
Gross Amounts of Recognized Assets	4,107	[1]	2,972	[1]
Gross Amounts Offset in Consolidated Balance Sheet		[1]		[1]
Net Amounts of Assets Presented in Consolidated Balance Sheet	4,107	[1]	2,972	[1]
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments	(3,851)	[1],[2]	(2,210)	[1],[2]
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Received	(212)	[1],[2]
Net Amount	44	[1]	762	[1]
Gross Amounts of Recognized Liabilities	(26,356)	[1]	(50,476)	[1]
Gross Amounts Offset in Consolidated Balance Sheet		[1]		[1]
Net Amounts of Liabilities Presented in Consolidated Balance Sheet	(26,356)	[1]	(50,476)	[1]
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments	3,851	[1],[2]	2,210	[1],[2]
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Pledged	22,505	[1],[2]	48,266	[1],[2]
TBAs
Offsetting Asset and Liabilities [Line Items]
Gross Amounts of Recognized Assets	745	[1]
Gross Amounts Offset in Consolidated Balance Sheet		[1]		[1]
Net Amounts of Assets Presented in Consolidated Balance Sheet	745	[1]
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments	(745)	[1],[2]
Gross Amounts of Recognized Liabilities	(5,810)	[1]
Gross Amounts Offset in Consolidated Balance Sheet		[1]		[1]
Net Amounts of Liabilities Presented in Consolidated Balance Sheet	(5,810)	[1]
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments	745	[1],[2]
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Pledged	4,726	[1],[2]
Net Amount	(339)	[1]
Futures
Offsetting Asset and Liabilities [Line Items]
Gross Amounts Offset in Consolidated Balance Sheet		[1]		[1]
Gross Amounts of Recognized Liabilities	(531)	[1]	(607)	[1]
Gross Amounts Offset in Consolidated Balance Sheet		[1]		[1]
Net Amounts of Liabilities Presented in Consolidated Balance Sheet	(531)	[1]	(607)	[1]
Gross Amounts Not Offset in Consolidated Balance Sheet, Cash Collateral Pledged	531	[1],[2]	607	[1],[2]
Loan warehouse debt
Offsetting Asset and Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(461,584)	[1]	(179,982)	[1]
Gross Amounts Offset in Consolidated Balance Sheet		[1]		[1]
Net Amounts of Liabilities Presented in Consolidated Balance Sheet	(461,584)	[1]	(179,982)	[1]
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments	461,584	[1],[2]	179,982	[1],[2]
Security repurchase agreements
Offsetting Asset and Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(371,201)	[1]	(371,936)	[1]
Gross Amounts Offset in Consolidated Balance Sheet		[1]		[1]
Net Amounts of Liabilities Presented in Consolidated Balance Sheet	(371,201)	[1]	(371,936)	[1]
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments	371,201	[1],[2]	371,936	[1],[2]
Commercial borrowings
Offsetting Asset and Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	(50,119)	[1]
Gross Amounts Offset in Consolidated Balance Sheet		[1]
Net Amounts of Liabilities Presented in Consolidated Balance Sheet	(50,119)	[1]
Gross Amounts Not Offset in Consolidated Balance Sheet, Financial Instruments	$ 50,119	[1],[2]

[1] Interest rate agreements, TBAs, and futures are components of derivatives instruments on our consolidated balances sheets. Loan warehouse debt, which is secured by residential mortgage loans, and security repurchase agreements are components of short-term debt on our consolidated balance sheets. Commercial borrowings are a component of long-term debt on our consolidated balance sheets.

[2] Amounts presented in these columns are limited in total to the net amount of assets or liabilities presented in the prior column by instrument. In certain cases, there is excess cash collateral or financial assets we have pledged to a counterparty that exceed the financial liabilities subject to a master netting arrangement or similar agreement. Additionally, in certain cases, counterparties have pledged excess cash collateral to us that exceeds our corresponding financial assets. In each case, these excess amounts are excluded from the table although they are separately reported in our consolidated balance sheets as assets or liabilities, respectively.