Servicing of Residential Loans - Schedule of Sensitivity Analysis of Fair Value, Servicing Rights Carried at Fair Value (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
10% adverse change on weighted-average discount rate	$ (41,926)	$ (68,874)
10% adverse change in weighted-average conditional prepayment rate	(30,513)	(63,884)
10% adverse change in weighted-average conditional default rate	(28,370)	(21,208)
20% adverse change in weighted-average discount rate	(80,512)	(132,645)
20% adverse change in weighted-average conditional prepayment rate	(59,083)	(123,173)
20% adverse change in weighted-average conditional default rate	$ (57,854)	$ (43,576)
Minimum [Member]
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Adverse Change In Assumptions Percent	10.00%
Maximum [Member]
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Adverse Change In Assumptions Percent	20.00%
Weighted Average [Member] | Servicing Rights Carried at Fair Value [Member]
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]
Weighted-average discount rate	11.56%	10.88%
Weighted-average conditional prepayment rate	9.09%	9.94%
Weighted-average conditional default rate	0.88%	1.06%