Financial Derivatives - Schedule of Derivative Instruments in Statement of Financial Position (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Notional Disclosures [Abstract]
Notional Amount	$ 14,022,179	$ 9,955,745
Fair Value
Asset	10,519	7,487
Collateral (held)/pledged	(2,685)	(1,778)
Net amount	7,834	5,709
(Liability)	(27,042)	(19,633)
Collateral (held)/pledged	132,129	47,018
Net amount	105,087	27,385
Designated as Hedging Instrument \| Fair value hedges: \| Pay fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	4,955,686	3,097,084
Fair Value
Asset	7,163	3,004
(Liability)	$ (3,281)	$ (4,326)
Weighted- Average Pay Rate	2.47%	2.42%
Weighted- Average Receive Rate	1.93%	2.58%
Weighted- Average Remaining Term (in years)	11 years 3 months 3 days	9 years 9 months
Designated as Hedging Instrument \| Fair value hedges: \| Receive fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 1,413,200	$ 1,871,200
Fair Value
Asset	76	547
(Liability)	$ (5,329)	$ (4,484)
Weighted- Average Pay Rate	1.88%	2.50%
Weighted- Average Receive Rate	2.13%	1.84%
Weighted- Average Remaining Term (in years)	1 year 3 months	1 year 6 months 29 days
Designated as Hedging Instrument \| Fair value hedges: \| Receive fixed callable
Notional Disclosures [Abstract]
Notional Amount	$ 524,000	$ 160,000
Fair Value
Asset	476	338
(Liability)	$ (772)	$ (28)
Weighted- Average Pay Rate	1.52%	2.35%
Weighted- Average Receive Rate	1.91%	3.06%
Weighted- Average Remaining Term (in years)	2 years 9 months 29 days	2 years 10 months 28 days
Designated as Hedging Instrument \| Cash flow hedges: \| Pay fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 428,000	$ 373,000
Fair Value
Asset	1,882	2,441
(Liability)	$ (1,514)	$ (99)
Weighted- Average Pay Rate	2.36%	2.40%
Weighted- Average Receive Rate	2.12%	2.83%
Weighted- Average Remaining Term (in years)	5 years 5 months 4 days	6 years 1 month 13 days
Not Designated as Hedging Instrument
Fair Value
Credit valuation adjustment	$ 0	$ (60)
Credit valuation adjustment	63	21
Not Designated as Hedging Instrument \| Pay fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	342,745	316,664
Fair Value
Asset	7	796
(Liability)	$ (14,046)	$ (10,399)
Weighted- Average Pay Rate	3.55%	3.69%
Weighted- Average Receive Rate	2.00%	2.52%
Weighted- Average Remaining Term (in years)	5 years 6 months 3 days	6 years 3 months
Not Designated as Hedging Instrument \| Receive fixed non-callable
Notional Disclosures [Abstract]
Notional Amount	$ 3,124,148	$ 2,347,371
Fair Value
Asset	49	0
(Liability)	$ (1,637)	$ 0
Weighted- Average Pay Rate	1.88%	2.37%
Weighted- Average Receive Rate	2.06%	2.10%
Weighted- Average Remaining Term (in years)	1 year 7 months 28 days	10 months 9 days
Not Designated as Hedging Instrument \| Receive fixed callable
Notional Disclosures [Abstract]
Notional Amount	$ 525,000
Fair Value
Asset	79
(Liability)	$ (80)
Weighted- Average Pay Rate	1.64%
Weighted- Average Receive Rate	1.68%
Weighted- Average Remaining Term (in years)	9 months 29 days
Not Designated as Hedging Instrument \| Basis swaps
Notional Disclosures [Abstract]
Notional Amount	$ 2,670,000	$ 1,770,026
Fair Value
Asset	787	421
(Liability)	$ (395)	$ (130)
Weighted- Average Pay Rate	1.86%	2.45%
Weighted- Average Receive Rate	1.76%	2.49%
Weighted- Average Remaining Term (in years)	10 months 24 days	1 year 3 months 7 days
Not Designated as Hedging Instrument \| Treasury futures
Notional Disclosures [Abstract]
Notional Amount	$ 39,400	$ 20,400
Fair Value
Asset		0
(Liability)	$ (51)	$ (188)
Weighted- Average Forward Price (in dollars per share)	$ 128.29	$ 121.09

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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.

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Nominal or face amount used to calculate payments on the derivative asset.

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- Definition

Average fixed interest rate related to the group of interest rate derivatives.

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Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Average variable interest rate related to the group of interest rate derivatives.

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Amount of credit risk valuation adjustment to derivative assets to properly reflect the credit quality of the counterparties.

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