Commitments and Contingencies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2017 USD ($) Trust	Mar. 31, 2016 USD ($)	Jan. 09, 2017	Dec. 31, 2016 USD ($)
Loss Contingencies [Line Items]
Percentage of maximum claim amount, repurchase threshold	98.00%
Reverse loans and real estate owned repurchased from securitization pools	$ 241,300,000	$ 127,000,000
Repurchased reverse loans and real estate owned held	$ 12,240,962,000			$ 12,416,542,000
Period Of Walter Energy Consolidated Group Tax Liability	2009 and prior tax years
Tax separation agreement date	Apr. 17, 2009
Period Of Walter Energy Proof Of Claim	August 31, 1983 through May 31, 1994
Walter Energy Federal Income Tax Years Under Audit	years ended May 31, 2000 through December 31, 2008
Walter Energy Additional Federal Income Tax Years under Audit	2009 through 2013 tax years
Percentage Of Equity Of Acquirer Of Walter Energy Core Assets Prospect Of Payment Exists			1.00%
Walter Energy Tax Year Under Audit	2009
Pending Litigation
Loss Contingencies [Line Items]
Loss contingency accrual	$ 41,000,000
Pending Litigation | Maximum
Loss Contingencies [Line Items]
Aggregate estimated amount of reasonably possible losses in excess of recorded liability	14,000,000
Pending Litigation | Minimum
Loss Contingencies [Line Items]
Aggregate estimated amount of reasonably possible losses in excess of recorded liability	0
Repurchased Reverse Loans And Real Estate Owned
Loss Contingencies [Line Items]
Repurchased reverse loans and real estate owned held	531,400,000
Reverse Mortgage | Curtailment Obligation Liability
Loss Contingencies [Line Items]
Loss contingency accrual	100,900,000
Loss contingency recorded in current period	400,000
Aggregate estimated amount of reasonably possible losses in excess of recorded liability	148,300,000
Reverse Mortgage | Additional Borrowing Capacity Floating Rate Reverse Loans
Loss Contingencies [Line Items]
Commitments	1,200,000,000
Commitment, capacity available to be drawn at March 31, 2017	1,000,000,000
Commitment, capacity eligible to be drawn through April 1, 2018	200,800,000
Reverse Mortgage | Additional Borrowing Capacity Fixed Rate Reverse Loans
Loss Contingencies [Line Items]
Commitments	400,000
Reverse Mortgage | Commitment To Fund Taxes and Insurance
Loss Contingencies [Line Items]
Commitments	28,400,000
Reverse Mortgage | Short Term Commitment To Lend
Loss Contingencies [Line Items]
Commitments	1,400,000
Reverse Mortgage | Commitment to Purchase Loans
Loss Contingencies [Line Items]
Commitments to purchase loans	2,300,000
Reverse Mortgage | Commitment to Sell Loans
Loss Contingencies [Line Items]
Commitments	12,000,000
Originations | Curtailment Obligation Liability
Loss Contingencies [Line Items]
Loss contingency accrual	18,500,000
Originations | Commitment to Purchase Loans
Loss Contingencies [Line Items]
Commitments to purchase loans	54,400,000
Originations | Commitment to Purchase Loans | Representations And Warranties
Loss Contingencies [Line Items]
Loss contingency accrual	21,600,000
Originations | Commitment to Purchase Loans | Representations And Warranties | Maximum
Loss Contingencies [Line Items]
Commitments	65,100,000,000
Originations | Commitment to Lend
Loss Contingencies [Line Items]
Commitments	2,400,000,000
Originations | Commitment To Sell Securities
Loss Contingencies [Line Items]
Commitments	3,200,000,000
Originations | Commitment to Purchase Mortgage Backed Securities
Loss Contingencies [Line Items]
Commitments to purchase loans	$ 400,000,000
VIE
Loss Contingencies [Line Items]
Number of securitization trusts with reimbursement obligations | Trust	11
Reimbursement obligation on LOC, if drawn	$ 165,000,000
Amount available on LOCs for securitization trusts	252,200,000
VIE Primary Beneficiary
Loss Contingencies [Line Items]
Repurchased reverse loans and real estate owned held	440,219,000			492,499,000
VIE Primary Beneficiary | Non-Residual Trusts
Loss Contingencies [Line Items]
Repurchased reverse loans and real estate owned held	$ 440,219,000			$ 450,377,000
VIE Primary Beneficiary | Non-Residual Trusts | Mandatory Clean-up Call For Residential Loans
Loss Contingencies [Line Items]
Mandatory clean-up calls required when loan pool falls to percent of original pincipal balance	10.00%
Expected period to exercise mandatory clean-up call obligation	2017 and continuing through 2019
Total residential loans expected to be called	$ 418,200,000
Estimated call obligations in 2017	101,400,000
Estimated call obligations in 2018	253,800,000
Estimated call obligations in 2019	63,000,000
Estimated call obligations in second quarter of 2017	9,900,000
Estimated call obligations in third quarter of 2017	18,800,000
Estimated call obligations in fourth quarter of 2017	$ 72,700,000