Servicing of Residential Loans - Schedule of Geographic Diversification of Third-Party Servicing Portfolio (Details) $ in Thousands	Dec. 31, 2018 USD ($) Account	Dec. 31, 2017 USD ($) Account
Concentration Risk [Line Items]
Number of Accounts | Account	1,479,167	1,678,493
Unpaid Principal Balance | $	$ 187,238,536	$ 207,864,813
Geographic Concentration Risk [Member] | Unpaid Principal Balance Serviced, Third Parties [Member]
Concentration Risk [Line Items]
Number of Accounts | Account	1,422,849	1,596,013
Unpaid Principal Balance | $	$ 177,761,736	$ 196,341,999
Percentage of Total	100.00%	100.00%
California [Member] | Geographic Concentration Risk [Member] | Unpaid Principal Balance Serviced, Third Parties [Member]
Concentration Risk [Line Items]
Number of Accounts | Account	163,609	181,126
Unpaid Principal Balance | $	$ 33,363,803	$ 35,774,862
Percentage of Total	18.80%	18.20%
Florida [Member] | Geographic Concentration Risk [Member] | Unpaid Principal Balance Serviced, Third Parties [Member]
Concentration Risk [Line Items]
Number of Accounts | Account	120,423	134,124
Unpaid Principal Balance | $	$ 14,700,373	$ 16,247,905
Percentage of Total	8.30%	8.30%
Texas [Member] | Geographic Concentration Risk [Member] | Unpaid Principal Balance Serviced, Third Parties [Member]
Concentration Risk [Line Items]
Number of Accounts | Account	116,621	127,442
Unpaid Principal Balance | $	$ 10,754,837	$ 11,378,660
Percentage of Total	6.00%	5.80%
Other Less Than 5% [Member] | Geographic Concentration Risk [Member] | Unpaid Principal Balance Serviced, Third Parties [Member]
Concentration Risk [Line Items]
Number of Accounts | Account	1,022,196	1,153,321
Unpaid Principal Balance | $	$ 118,942,723	$ 132,940,572
Percentage of Total	66.90%	67.70%