Finance of America Companies Inc. Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Fair Value - Summary of Commercial Mortgage Portfolio Lending (Detail)

Fair Value - Summary of Commercial Mortgage Portfolio Lending (Detail) - Commercial Mortgage Portfolio Lending [Member]	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Minimum [Member] \| Prepayment Rate [Member]
Fair Value Portfolio Mortgage Loans Classified Under Mortgage Loans Held For Sale Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]
Prepayment rate (CPR)	0.00%	0.00%
Minimum [Member] \| Default Rate [Member]
Fair Value Portfolio Mortgage Loans Classified Under Mortgage Loans Held For Sale Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]
Default rate (CDR)	1.00%	1.00%
Maximum [Member] \| Prepayment Rate [Member]
Fair Value Portfolio Mortgage Loans Classified Under Mortgage Loans Held For Sale Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]
Prepayment rate (CPR)	14.80%	15.00%
Maximum [Member] \| Default Rate [Member]
Fair Value Portfolio Mortgage Loans Classified Under Mortgage Loans Held For Sale Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]
Default rate (CDR)	45.40%	42.70%
Weighted Average [Member] \| Prepayment Rate [Member]
Fair Value Portfolio Mortgage Loans Classified Under Mortgage Loans Held For Sale Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]
Prepayment rate (CPR)	5.90%	9.30%
Weighted Average [Member] \| Measurement Input, Discount Rate [Member]
Fair Value Portfolio Mortgage Loans Classified Under Mortgage Loans Held For Sale Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]
Discount rate	3.80%	4.90%
Weighted Average [Member] \| Default Rate [Member]
Fair Value Portfolio Mortgage Loans Classified Under Mortgage Loans Held For Sale Measured On Recurring And Nonrecurring Basis Fair Value Measurement [Line Items]
Default rate (CDR)	2.90%	2.00%