Derivatives (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2023	Dec. 31, 2022
Derivative [Line Items]
Notional amount of derivatives	$ 7,489,184	$ 7,936,239
Fair value liability	1,400	1,900
Credit risk-related contingent features, net liability position	70,000	8,700
Credit risk-related contingent features, posted collateral	73,000	8,500
Derivatives Designated as Hedging Instruments [Member]
Derivative [Line Items]
Notional amount of derivatives	2,063,500	2,816,000
Interest Rate Swaps [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Cash Flow Hedge [Member]
Derivative [Line Items]
Amortization of accumulated other comprehensive loss on terminated cash flow hedges	2,900
Interest Rate Swaps [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Cash Flow Hedge [Member] \| Swap Agreement 3, Expires 2025 [Member]
Derivative [Line Items]
Notional amount of derivatives	$ 50,000
Derivative maturity expiration year	2025
Interest Rate Swaps [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Cash Flow Hedge [Member] \| Swap Agreement 4, Expires 2026 [Member]
Derivative [Line Items]
Notional amount of derivatives	$ 475,000
Derivative maturity expiration year	2026
Interest Rate Swaps [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Cash Flow Hedge [Member] \| Swap Agreement 5, Expires 2027 [Member]
Derivative [Line Items]
Notional amount of derivatives	$ 925,000
Derivative maturity expiration year	2027
Interest Rate Swaps [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Cash Flow Hedge [Member] \| Swap Agreement 6, Expires Thereafter [Member]
Derivative [Line Items]
Notional amount of derivatives	$ 100,000
Interest Rate Swaps [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Fair Value Hedging [Member]
Derivative [Line Items]
Amortization of accumulated other comprehensive loss on terminated cash flow hedges	16,600
Interest Rate Swaps - Securities [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Fair Value Hedging [Member]
Derivative [Line Items]
Notional amount of derivatives	513,500	$ 716,000
Derivative hedged item	494,500
Basis adjustment associated with hedged items	19,000
Interest Rate Swaps - Securities [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Fair Value Hedging [Member] \| Commercial Mortgage-Backed Securities [Member]
Derivative [Line Items]
Amortized cost basis of closed portfolio of pre-payable securities	$ 559,200

Derivative, Maturity Year

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- Definition

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (d)
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- Definition

Amount of hedged item in hedging relationship. Excludes hedged asset or liability.

+ References

No definition available.

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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.

+ References

No definition available.

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- Definition

The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=125515794&loc=SL5624258-113959

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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
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- Definition

Amount of cumulative increase (decrease) in fair value of hedged asset in fair value hedge, attributable to hedged risk, in last-of-layer hedging relationship.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4EEE
-Subparagraph (c)
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- Definition

Fair value of financial and nonfinancial obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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- Definition

Amortized cost of closed portfolio of prepayable financial asset, used to designate hedging relationship in which hedged item is last layer expected to be remaining at end of hedging relationship.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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- Definition

Amount of unrealized gain (loss) related to the increase or decrease in fair value of interest rate derivatives designated as cash flow hedging instruments, which was recorded in accumulated other comprehensive income to the extent that the cash flow hedge was determined to be effective.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 815
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-Section 50
-Paragraph 4C
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