Mortgage servicing rights - Schedule of Changes in Mortgage Servicing Rights (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Servicing Asset at Fair Value, Amount [Roll Forward]
Carrying value at beginning of period	$ 88,829	$ 76,107	$ 32,070
Fair value impact of change in accounting policy (See Note 1)		0	0	$ 1,011
Carrying value at beginning of period		88,829	76,107	$ 33,081
Capitalization	42,151	54,913	58,984
Sales	(29,160)	(39,428)	(11,686)
Loss on sale	0	0	(249)
Change in fair value:
Due to pay-offs/pay-downs	(16,350)	(11,062)	(3,104)
Due to change in valuation inputs or assumptions	(9,949)	8,299	(919)
Carrying value at end of period	$ 75,521	$ 88,829	$ 76,107

Servicing asset amortized value to fair value adjustment.

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- Definition

Servicing asset at amortized value gain (loss) on sale.

+ References

No definition available.

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Servicing asset at fair value, changes in fair value due to pay-offs or pay-downs.

+ References

No definition available.

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- Definition

Amortized amount of 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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Amount of additions from purchases, assumption or transfer to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Amount conveyed to unrelated parties of contract to 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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- 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.

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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.

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