Commitments and Contingent Liabilities (Details) - USD ($) $ in Thousands			12 Months Ended
	Jun. 30, 2030	Jun. 30, 2025	Dec. 31, 2020
Guarantor Obligations [Line Items]
Within one year			$ 9,084,582
One to three years			404,020
Three to five years			157,289
Over five years			216,951
Total			9,862,842
Deposits Without a Stated Maturity
Guarantor Obligations [Line Items]
Within one year			8,211,443
Total			8,211,443
Time Deposits
Guarantor Obligations [Line Items]
Within one year			526,641
One to three years			376,825
Three to five years			74,294
Total			977,760
Borrowed Funds
Guarantor Obligations [Line Items]
Within one year			326,726
Three to five years			70,000
Over five years			200,000
Total			596,726
Operating Lease Obligations
Guarantor Obligations [Line Items]
Within one year			8,342
One to three years			12,741
Three to five years			9,283
Over five years			9,500
Total			39,866
Outside Data Processing
Guarantor Obligations [Line Items]
Within one year			4,592
One to three years			8,190
Three to five years			1,677
Total			14,459
George Mason Sponsorship
Guarantor Obligations [Line Items]
Within one year			675
One to three years			1,350
Three to five years			1,363
Over five years			6,775
Total			10,163
George Mason Sponsorship | Termination Option One
Guarantor Obligations [Line Items]
Increase (decrease) in contractual obligation, termination option			$ 3,500
George Mason Sponsorship | Termination Option One | Minimum
Guarantor Obligations [Line Items]
Contractual obligation, option period			11 years
George Mason Sponsorship | Termination Option One | Maximum
Guarantor Obligations [Line Items]
Contractual obligation, option period			15 years
George Mason Sponsorship | Termination Option Two
Guarantor Obligations [Line Items]
Increase (decrease) in contractual obligation, termination option			$ 3,600
George Mason Sponsorship | Termination Option Two | Minimum
Guarantor Obligations [Line Items]
Contractual obligation, option period			16 years
George Mason Sponsorship | Termination Option Two | Maximum
Guarantor Obligations [Line Items]
Contractual obligation, option period			20 years
George Mason Sponsorship | Forecast
Guarantor Obligations [Line Items]
Option to terminate	15 years	10 years
D.C. United
Guarantor Obligations [Line Items]
Within one year			$ 820
One to three years			844
Total			1,664
LIHTC Investments
Guarantor Obligations [Line Items]
Within one year			5,343
One to three years			2,070
Three to five years			672
Over five years			676
Total			8,761
Other Investments
Guarantor Obligations [Line Items]
Within one year			0
One to three years			2,000
Three to five years			0
Over five years			0
Total			$ 2,000