Derivatives and Hedging Activities - Effect of derivatives in hedging relationships (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense	$ 13,319	$ 21,277	$ 45,561	$ 63,531
Fair value hedging \| Interest expense
Gains (losses) on fair value hedging relationships:
Amounts related to interest settlements on derivatives	24	(97)	51	(300)
Recognized on derivatives	(114)	71	1,068	671
Recognized on hedged items	(5)	(55)	(996)	(668)
Net income (expense) recognized on fair value hedges	(95)	(81)	123	(297)
Cash flow hedging \| Interest expense
Gains (losses) on active cash flow hedging relationships:
Realized gains (losses) reclassified from AOCI into net income	(130)	0	(197)	0
Net income (expense) recognized on cash flow hedges	(130)	$ 0	(197)	$ 0
Premium amortization expense excluded from assessment of hedge effectiveness	$ 119		$ 211

Gain (Loss) On Cash Flow Hedges Recognized In Earnings

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Gain (Loss) On Derivative Interest Settlement

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Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

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Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Total amount of gain (loss) derived from fair value hedges recognized in earnings in the period.

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Amount of the cost of borrowed funds accounted for as interest expense.

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The amount of net gains or losses on interest rate cash flow hedges reclassified during the period to earnings from accumulated other comprehensive income upon the hedged transaction affecting earnings.

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The loss relating to components of the gain (loss) on the cash flow hedging instrument excluded from the assessment of cash flow hedge effectiveness. Recognized in earnings.

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