Borrowings (Long Term Debt) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Debt Instrument [Line Items]
Notes and subordinated debt	$ 1,039,651	$ 1,039,651		$ 1,059,778
Debt issuance cost on senior fixed-rates	(1,612)	(1,612)		(1,824)
Long-term debt	$ 1,052,258	1,052,258		$ 1,073,128
Proceeds from extinguishment of borrowings		$ 698	$ 0
Variable interest rate	8.46%	8.46%		7.69%
LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	2.95%	2.95%
Senior Notes
Debt Instrument [Line Items]
Discount on senior fixed-rate notes	$ (647)	$ (647)		$ (756)
Senior Notes | Senior Notes Due 2024
Debt Instrument [Line Items]
Senior notes, interest rate (as a percent)	4.375%	4.375%
Notes and subordinated debt	$ 132,550	$ 132,550		150,000
Shares repurchased and retired	$ 17,500
Price of senior notes (in dollars per share)	$ 0.96
Proceeds from extinguishment of borrowings	$ 700
Senior Notes | Senior Notes Due 2029
Debt Instrument [Line Items]
Senior notes, interest rate (as a percent)	4.10%	4.10%
Notes and subordinated debt	$ 330,781	$ 330,781		333,458
Hedge basis adjustment	30,800	30,800		33,500
Subordinated Debt
Debt Instrument [Line Items]
Premium on subordinated fixed-to-floating rate notes	$ 14,866	$ 14,866		15,930
Subordinated Debt | Subordinated Notes Due 2029
Debt Instrument [Line Items]
Senior notes, interest rate (as a percent)	4.00%	4.00%
Notes and subordinated debt	$ 274,000	$ 274,000		274,000
Subordinated Debt | Subordinated Notes Due 2030
Debt Instrument [Line Items]
Senior notes, interest rate (as a percent)	3.875%	3.875%
Notes and subordinated debt	$ 225,000	$ 225,000		225,000
Junior subordinated debt
Debt Instrument [Line Items]
Notes and subordinated debt	77,320	77,320		77,320
Long-term Debt
Debt Instrument [Line Items]
Hedge basis adjustment	$ 30,781	$ 30,781		$ 33,458