Fair Value (Tables)

12 Months Ended

Dec. 31, 2022

Fair Value

Schedule of financial assets and liabilities measured on a recurring basis

			Fair Value Measurements Using
					Significant
			Quoted Prices in		Other		Significant
			Active Markets for		Observable		Unobservable
			Identical Assets		Inputs		Inputs
	Balance		(Level 1)		(Level 2)		(Level 3)
	(Dollars in thousands)
Assets at December 31, 2022
Available-for-sale securities:
U.S. Treasury	$	418,474	$	418,474	$	—	$	—
Agency mortgage-backed securities		71,122		—		71,122		—
I/O strip receivables		152		—		152		—
Assets at December 31, 2021
Available-for-sale securities:
Agency mortgage-backed securities	$	102,252	$	—	$	102,252	$	—
I/O strip receivables		221		—		221		—

Schedule of carrying amounts and estimated fair values of financial instruments

			Estimated Fair Value
					Significant
			Quoted Prices in		Other		Significant
			Active Markets for		Observable		Unobservable
	Carrying		Identical Assets		Inputs		Inputs
	Amounts		(Level 1)		(Level 2)		(Level 3)		Total
	(Dollars in thousands)
Assets:
Cash and cash equivalents	$	306,603	$	306,603	$	—	$	—	$	306,603
Securities available-for-sale		489,596		418,474		71,122		—		489,596
Securities held-to-maturity, net		714,990		—		614,452		—		614,452
Loans (including loans held-for-sale), net		3,253,494		—		2,456		3,080,485		3,082,941
FHLB stock, FRB stock, and other
investments		32,522		—		—		—		N/A
Accrued interest receivable		15,047		1,328		1,836		11,883		15,047
I/O strips receivables		152		—		152		—		152
Liabilities:
Time deposits	$	143,958	$	—	$	144,702	$	—	$	144,702
Other deposits		4,245,646		—		4,245,646		—		4,245,646
Subordinated debt		39,350		—		36,025		—		36,025
Accrued interest payable		600		—		600		—		600

			Estimated Fair Value
					Significant
			Quoted Prices in		Other		Significant
			Active Markets for		Observable		Unobservable
	Carrying		Identical Assets		Inputs		Inputs
	Amounts		(Level 1)		(Level 2)		(Level 3)		Total
	(Dollars in thousands)
Assets:
Cash and cash equivalents	$	1,306,216	$	1,306,216	$	—	$	—	$	1,306,216
Securities available-for-sale		102,252		—		102,252		—		102,252
Securities held-to-maturity, net		658,397		—		657,649		—		657,649
Loans (including loans held-for-sale), net		3,046,403		—		2,367		3,061,558		3,063,925
FHLB stock, FRB stock, and other
investments		32,504		—		—		—		N/A
Accrued interest receivable		10,781		—		1,719		9,062		10,781
I/O strips receivables		221		—		221		—		221
Liabilities:
Time deposits	$	139,834	$	—	$	140,086	$	—	$	140,086
Other deposits		4,619,578		—		4,619,578		—		4,619,578
Subordinated debt		39,925		—		40,425		—		40,425
Accrued interest payable		477		—		477		—		477