Income taxes - Schedule of Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Deferred tax assets:
Allowance for credit losses	$ 40,878	$ 48,409
Operating lease liabilities	13,067	14,496
Federal net operating loss	1,753	1,753
Deferred compensation	8,572	8,872
Unrealized loss on cash flow hedges	364	499
Other	19,817	19,101
Subtotal	84,451	93,130
Deferred tax liabilities:
FHLB stock dividends	(561)	(561)
Operating leases - right of use assets	(11,831)	(13,197)
Depreciation	(7,088)	(7,491)
Amortization of core deposit intangibles	(349)	(684)
Unrealized gain on equity securities	(3,877)	(17)
Unrealized gain on debt securities	(5,987)	(13,027)
Mortgage servicing rights	(26,435)	(20,803)
Goodwill	(12,522)	(11,301)
Other	(9,828)	(9,653)
Subtotal	(78,478)	(76,734)
Net deferred tax assets	$ 5,973	$ 16,396

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Deferred tax liabilities, federal home loan bank stock dividends.

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Amount of deferred tax liability attributable to taxable temporary differences.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary difference from allowance for credit loss on financing receivable.

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Amount of deferred tax liability attributable to taxable temporary differences from investments (excludes investments in subsidiaries and equity method investments).

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Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment.

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