Derivatives and hedging activities - Offsetting Derivatives (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Offsetting of Derivative Assets
Gross Amounts of Recognized Assets	$ 10,690	$ 15,371
Net Amounts of Assets presented in the Balance Sheet	10,690	15,371
Gross Amounts Not Offset in the Statement of Financial Position - Financial Instruments	3,029	1,678
Net Amount	7,661	13,693
Offsetting of Derivative Liabilities
Gross Amounts of Recognized Liabilities	9,277	14,099
Net Amounts of Assets presented in the Balance Sheet	9,277	14,099
Gross Amounts Not Offset in the Statement of Financial Position - Financial Instruments	3,029	1,678
Gross Amounts Not Offset in the Statement of Financial Position - Cash Collateral Paid		$ 12,421
Net Amount	$ 6,248

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