Fair Value - Level 3 Unobservable Inputs, Mortgage Loans and IRLC (Details) $ in Thousands	Mar. 31, 2021 USD ($) item	Dec. 31, 2020 USD ($) item
Excess servicing spread financing
Loans held for sale | $	$ 13,385,789	$ 11,616,400
Level 3
Excess servicing spread financing
Loans held for sale | $	$ 5,202,065	$ 4,675,169
Loans held for sale | Discount rate | Level 3 | Minimum
Excess servicing spread financing
Input	2.6	2.8
Loans held for sale | Discount rate | Level 3 | Maximum
Excess servicing spread financing
Input	9.2	9.2
Loans held for sale | Discount rate | Level 3 | Weighted average
Excess servicing spread financing
Input	2.6	2.8
Loans held for sale | Twelve-month projected housing price index Change | Level 3 | Minimum
Excess servicing spread financing
Input	3.9	2.7
Loans held for sale | Twelve-month projected housing price index Change | Level 3 | Maximum
Excess servicing spread financing
Input	4.9	3.5
Loans held for sale | Twelve-month projected housing price index Change | Level 3 | Weighted average
Excess servicing spread financing
Input	4.4	3.0
Loans held for sale | Prepayment/resale speed | Level 3 | Minimum
Excess servicing spread financing
Input	0.3	0.4
Loans held for sale | Prepayment/resale speed | Level 3 | Maximum
Excess servicing spread financing
Input	29.5	31.3
Loans held for sale | Prepayment/resale speed | Level 3 | Weighted average
Excess servicing spread financing
Input	21.2	21.9
Loans held for sale | Total prepayment speed | Level 3 | Minimum
Excess servicing spread financing
Input	0.3	0.5
Loans held for sale | Total prepayment speed | Level 3 | Maximum
Excess servicing spread financing
Input	40.2	42.9
Loans held for sale | Total prepayment speed | Level 3 | Weighted average
Excess servicing spread financing
Input	28.1	29.2
Interest rate lock commitments | Level 3
Excess servicing spread financing
Loans held for sale | $	$ 337,940	$ 677,026
Interest rate lock commitments | Pull-through rate | Level 3 | Minimum
Excess servicing spread financing
Input	8.0	10.1
Interest rate lock commitments | Pull-through rate | Level 3 | Maximum
Excess servicing spread financing
Input	100	100
Interest rate lock commitments | Pull-through rate | Level 3 | Weighted average
Excess servicing spread financing
Input	85.5	82.7
Interest rate lock commitments | Mortgage servicing rights value expressed as servicing fee multiple | Level 3 | Minimum
Excess servicing spread financing
Input	(10.0)	0.7
Interest rate lock commitments | Mortgage servicing rights value expressed as servicing fee multiple | Level 3 | Maximum
Excess servicing spread financing
Input	6.4	5.3
Interest rate lock commitments | Mortgage servicing rights value expressed as servicing fee multiple | Level 3 | Weighted average
Excess servicing spread financing
Input	4.1	3.6
Interest rate lock commitments | Percentage of unpaid principal balance | Level 3 | Minimum
Excess servicing spread financing
Input	(2.1)	0.1
Interest rate lock commitments | Percentage of unpaid principal balance | Level 3 | Maximum
Excess servicing spread financing
Input	3.2	2.6
Interest rate lock commitments | Percentage of unpaid principal balance | Level 3 | Weighted average
Excess servicing spread financing
Input	1.3	1.2