Fair Value - Carrying Values and Estimated Fair Values of Financial Assets and Liabilities Required to be Disclosed at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011
Fair Value And Carrying Value By Balance Sheet Grouping [Line Items]
Cash and cash equivalents	$ 532,620	$ 442,054	$ 36,892	$ 18,739
Restricted cash and cash equivalents	1,057,503	653,338
Residential loans at amortized cost	1,443,707	1,490,321
Insurance premium receivables	106,734	107,824
Servicer and protective advances, net	1,044,410	173,047
Payables to insurance carriers	67,548	51,377
Servicer payables	959,565	587,929
Servicing advance liabilities (1)	737,629	100,164
Debt (2)	3,625,115	1,146,249
Carrying Amount [Member] | Level 1 [Member]
Fair Value And Carrying Value By Balance Sheet Grouping [Line Items]
Cash and cash equivalents	532,620	442,054
Restricted cash and cash equivalents	1,057,503	653,338
Other	111,397	97,210
Other	548,078	183,885
Servicer payables	959,565	587,929
Carrying Amount [Member] | Level 3 [Member]
Fair Value And Carrying Value By Balance Sheet Grouping [Line Items]
Residential loans at amortized cost	1,443,707	1,490,321
Insurance premium receivables	106,734	107,824
Servicer and protective advances, net	1,044,410	173,047
Payables to insurance carriers	67,548	51,377
Servicing advance liabilities (1)	737,100	99,508
Mortgage-backed debt carried at amortized cost (3)	1,244,458	1,298,999
Carrying Amount [Member] | Level 2 [Member]
Fair Value And Carrying Value By Balance Sheet Grouping [Line Items]
Debt (2)	3,588,254	1,115,804
Estimated Fair Value [Member] | Level 1 [Member]
Fair Value And Carrying Value By Balance Sheet Grouping [Line Items]
Cash and cash equivalents	532,620	442,054
Restricted cash and cash equivalents	1,057,503	653,338
Other	111,397	97,210
Other	548,078	183,885
Servicer payables	959,565	587,929
Estimated Fair Value [Member] | Level 3 [Member]
Fair Value And Carrying Value By Balance Sheet Grouping [Line Items]
Residential loans at amortized cost	1,389,137	1,436,592
Insurance premium receivables	101,347	101,238
Servicer and protective advances, net	1,003,524	160,632
Payables to insurance carriers	66,617	50,614
Servicing advance liabilities (1)	737,181	99,915
Mortgage-backed debt carried at amortized cost (3)	1,249,739	1,300,979
Estimated Fair Value [Member] | Level 2 [Member]
Fair Value And Carrying Value By Balance Sheet Grouping [Line Items]
Debt (2)	$ 3,646,543	$ 1,165,811