Mortgage Servicing Rights ("MSRs") (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Servicing Asset at Fair Value, Amount [Roll Forward]
Balance at beginning of the period	$ 73,504	$ 71,022	$ 85,638	$ 75,183
Additions from loans sold with servicing retained	20,351	9,802	29,798	16,382
Additions from acquisitions	0	407	0	407
Estimate of changes in fair value due to:
Payoffs and paydowns	(8,670)	(4,076)	(15,694)	(6,073)
Changes in valuation inputs or assumptions	(7,982)	(4,305)	(22,539)	(13,049)
Fair value at end of the period	77,203	72,850	77,203	72,850
Unpaid principal balance of mortgage loans serviced for others	$ 9,188,285	$ 7,515,186	$ 9,188,285	$ 7,515,186

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

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- Definition

The value of new servicing assets, subsequently measured at fair value, acquired or created during the current period through purchases or from transfers of financial assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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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
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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

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

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

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