Mortgage Servicing Rights ("MSRs") (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Servicing Asset at Fair Value, Amount [Roll Forward]
Balance at beginning of the period	$ 92,081	$ 85,638
Additions from loans sold with servicing retained	24,616	9,447
Estimate of changes in fair value due to:
Early buyout options (“EBO”) exercised	(258)	0
Payoffs and paydowns	(10,168)	(7,024)
Changes in valuation inputs or assumptions	18,045	(14,557)
Fair value at end of the period	124,316	73,504
Unpaid principal balance of mortgage loans serviced for others	$ 11,530,676	$ 8,314,634

This is the sum of principal amount outstanding for both securitized and unsecuritized loans of all types.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Section 50
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- Definition

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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Amount of increase (decrease) in fair value from changes in the inputs, assumptions, or model used to calculate the fair value of the contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
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- References

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- Definition

Decrease in servicing assets subsequently measured at fair value resulting from conveyance of servicing rights to unrelated parties.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Servicing Asset at Fair Value, Early Buyout Option

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Servicing Assets At Fair Value, Additions From Loans Sold With Servicing Retained

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