Investment Securities - Securities Held-to-Maturity Credit Quality Indicators (Details) - USD ($) $ in Thousands	Jun. 30, 2023		Dec. 31, 2022
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	$ 2,279,702	[1]	$ 2,270,635	[2]
Standard & Poor's, AAA Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	900,254		914,499
Standard & Poor's, AA+ Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	1,019,659		997,563
Standard & Poor's, AA Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	166,760		173,751
Standard & Poor's, A Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	1,894		1,901
Standard & Poor's, A- Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		23,244
Standard & Poor's, BBB Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	44,306		20,999
Standard & Poor's, No Credit Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	48,751		43,207
Standard & Poor's, AA- Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	86,060		95,471
Standard & Poor's, A+ Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	12,018		0
Municipal securities
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	1,245,462		1,243,443
Municipal securities | Standard & Poor's, AAA Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	552,131		568,674
Municipal securities | Standard & Poor's, AA+ Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	403,500		385,990
Municipal securities | Standard & Poor's, AA Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	166,760		173,751
Municipal securities | Standard & Poor's, A Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	1,894		1,901
Municipal securities | Standard & Poor's, A- Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Municipal securities | Standard & Poor's, BBB Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Municipal securities | Standard & Poor's, No Credit Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	23,099		17,656
Municipal securities | Standard & Poor's, AA- Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	86,060		95,471
Municipal securities | Standard & Poor's, A+ Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	12,018		0
Agency commercial MBS
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	430,578		427,411
Agency commercial MBS | Standard & Poor's, AAA Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Agency commercial MBS | Standard & Poor's, AA+ Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	430,578		427,411
Agency commercial MBS | Standard & Poor's, AA Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Agency commercial MBS | Standard & Poor's, A Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Agency commercial MBS | Standard & Poor's, A- Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Agency commercial MBS | Standard & Poor's, BBB Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Agency commercial MBS | Standard & Poor's, No Credit Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Agency commercial MBS | Standard & Poor's, AA- Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Agency commercial MBS | Standard & Poor's, A+ Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Private label commercial MBS
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	348,123		345,825
Private label commercial MBS | Standard & Poor's, AAA Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	348,123		345,825
Private label commercial MBS | Standard & Poor's, AA+ Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Private label commercial MBS | Standard & Poor's, AA Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Private label commercial MBS | Standard & Poor's, A Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Private label commercial MBS | Standard & Poor's, A- Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Private label commercial MBS | Standard & Poor's, BBB Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Private label commercial MBS | Standard & Poor's, No Credit Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Private label commercial MBS | Standard & Poor's, AA- Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Private label commercial MBS | Standard & Poor's, A+ Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
U.S. Treasury securities
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	185,581		184,162
U.S. Treasury securities | Standard & Poor's, AAA Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
U.S. Treasury securities | Standard & Poor's, AA+ Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	185,581		184,162
U.S. Treasury securities | Standard & Poor's, AA Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
U.S. Treasury securities | Standard & Poor's, A Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
U.S. Treasury securities | Standard & Poor's, A- Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
U.S. Treasury securities | Standard & Poor's, BBB Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
U.S. Treasury securities | Standard & Poor's, No Credit Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
U.S. Treasury securities | Standard & Poor's, AA- Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
U.S. Treasury securities | Standard & Poor's, A+ Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Corporate Debt Securities
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	69,958		69,794
Corporate Debt Securities | Standard & Poor's, AAA Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Corporate Debt Securities | Standard & Poor's, AA+ Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Corporate Debt Securities | Standard & Poor's, AA Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Corporate Debt Securities | Standard & Poor's, A Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Corporate Debt Securities | Standard & Poor's, A- Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		23,244
Corporate Debt Securities | Standard & Poor's, BBB Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	44,306		20,999
Corporate Debt Securities | Standard & Poor's, No Credit Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	25,652		25,551
Corporate Debt Securities | Standard & Poor's, AA- Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	0		0
Corporate Debt Securities | Standard & Poor's, A+ Rating
Schedule of Held-to-maturity Securities [Line Items]
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss	$ 0		$ 0

[1] Excludes accrued interest receivable of $13.4 million at June 30, 2023 which is recorded in "Other assets" on the condensed consolidated balance sheets

[2] Excludes accrued interest receivable of $13.5 million at December 31, 2022 which is recorded in "Other assets" on the condensed consolidated balance sheets