Debt Securities Available for Sale - Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($) security	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) security	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) security
Debt Securities, Available-for-sale [Line Items]
Mortgage-backed securities and collateralized mortgage obligations	$ 1,026,493,000		$ 1,026,493,000
Mortgage-backed securities and collateralized mortgage obligations	844,260,000		844,260,000
Proceeds from sales of debt securities available for sale	0	$ 0	277,022,000	$ 126,772,000
Gross gains on sale of available-for-sale securities			0	210,000
Gross losses on sale of available-for-sale securities			10,800,000	0
Proceeds from maturities and calls of debt securities, available-for-sale	0		0
Proceeds from calls of debt securities, available-for-sale		0		0
Proceeds from maturities of debt securities, available-for-sale		$ 915,000		$ 915,000
Debt securities, available-for-sale, restricted	$ 207,100,000		$ 207,100,000		$ 724,000,000
Number of securities in unrealized loss position | security	273		273		455
Accrued interest receivable on debt securities available for sale	$ 3,800,000		$ 3,800,000		$ 3,200,000
Corporate debt securities | Non-investment grade
Debt Securities, Available-for-sale [Line Items]
Accrued interest receivable on debt securities available for sale	7,000,000		7,000,000
Subsidiaries
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, restricted	$ 71,500,000		$ 71,500,000		$ 28,300,000