Loans Held For Sale (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Held-for-Sale	$ 5,635.1	$ 0.0
Pledged Assets Separately Reported, Loans Pledged as Collateral, at Fair Value	0.0
MSR capitalized upon sale of loan	763.8
Proceeds from Sale of Mortgage Loans Held-for-sale	(465.3)
Provision for and change in estimate of liability for losses under representations and warranties	(0.6)
Change in fair value of loans held for sale	(0.3)
Unrealized Gain (Loss) on Derivatives	(69.9)
Derivative Instruments Not Designated as Hedging Instruments, Gain	20.1
Gain (Loss) on Sales of Loans, Net	247.8
Loan acquisition and origination fees	78.4
Net gain on loan origination and sale activities	326.2	$ 0.0	$ 0.0
Non-agency
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Held-for-Sale	62.8
Purchased from Ginnie Mae
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Held-for-Sale	1,692.8
Purchased from correspondent seller
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Held-for-Sale	1,396.6
Loans Insured or Guaranteed by US Government Authorities
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Held-for-Sale	3,089.4
US Government Agency Insured Loans
Loans and Leases Receivable Disclosure [Line Items]
Financing Receivable, Held-for-Sale	$ 2,482.9