Quarterly report pursuant to Section 13 or 15(d)

Fair Value - Summary of the fair value and unpaid principal balance ("UPB") (Detail)

v3.22.2
Fair Value - Summary of the fair value and unpaid principal balance ("UPB") (Detail) - USD ($)
$ in Thousands
Jun. 30, 2022
Dec. 31, 2021
Estimated Fair Value    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Estimated Fair Value $ 10,882,441 $ 10,556,054
Unpaid Principal Balance 10,468,472 9,849,835
Mortgage Loans Held For Investment Subject To Nonrecourse Debt [Member] | Estimated Fair Value | Reverse Mortgage Loans [Member]    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Estimated Fair Value 6,149,706 5,823,301
Unpaid Principal Balance 6,053,167 5,165,479
Mortgage Loans Held For Investment Subject To Nonrecourse Debt [Member] | Estimated Fair Value | Commercial Mortgage Loans [Member]    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Estimated Fair Value 451,056 394,893
Mortgage Loans Held For Investment Subject To Nonrecourse Debt [Member] | Unpaid Principal Balance | Commercial Mortgage Loans [Member]    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Unpaid Principal Balance 451,981 388,788
Mortgage Loans Held For Investment [Member] | Estimated Fair Value | Reverse Mortgage Loans [Member]    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Estimated Fair Value 949,551 940,604
Unpaid Principal Balance 871,671 815,426
Mortgage Loans Held For Investment [Member] | Estimated Fair Value | Commercial Mortgage Loans [Member]    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Estimated Fair Value 108,859 90,724
Mortgage Loans Held For Investment [Member] | Unpaid Principal Balance | Commercial Mortgage Loans [Member]    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Unpaid Principal Balance 108,322 89,267
Mortgage Loans Held For Sale [Member] | Estimated Fair Value | Commercial Mortgage Loans [Member]    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Estimated Fair Value 233,249 149,426
Mortgage Loans Held For Sale [Member] | Estimated Fair Value | Residential Mortgage Loans [Member]    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Estimated Fair Value 996,345 1,902,952
Mortgage Loans Held For Sale [Member] | Unpaid Principal Balance | Commercial Mortgage Loans [Member]    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Unpaid Principal Balance 239,108 145,463
Mortgage Loans Held For Sale [Member] | Unpaid Principal Balance | Residential Mortgage Loans [Member]    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Unpaid Principal Balance 988,361 1,859,788
HMBS Related Obligations [Member] | Estimated Fair Value    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Estimated Fair Value 10,745,879 10,422,358
HMBS Related Obligations [Member] | Unpaid Principal Balance    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Unpaid Principal Balance 10,445,730 9,849,835
Non Recourse Debt [Member] | Estimated Fair Value    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Estimated Fair Value 6,447,238 5,857,069
Non Recourse Debt [Member] | Unpaid Principal Balance    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Unpaid Principal Balance 6,773,313 5,709,946
Nonrecourse Commercial Loan [Member] | Unpaid Principal Balance    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Estimated Fair Value 162,464 111,738
Unpaid Principal Balance 158,659 107,744
Nonrecourse Mortgage Service Rights [Member] | Unpaid Principal Balance    
Fair Value Summary Of The Fair Value And Unpaid Principal Balance Upb [Line Items]    
Estimated Fair Value 142,382 142,435
Unpaid Principal Balance $ 142,382 $ 142,435