Fair Value of Assets and Liabilities - Carrying Amount and Estimated Fair Value of Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Carrying Amount
Financial assets
Cash and cash equivalents	$ 415,406	$ 437,686
Debt securities, held-to-maturity	3,788,486	1,199,164
Loans receivable, net of ACL	14,226,792	13,259,366
Total financial assets	18,430,684	14,896,216
Financial liabilities
Term deposits	968,382	1,036,077
FHLB advances	580,000
Repurchase agreements and other borrowed funds	1,034,397	1,064,888
Subordinated debentures	132,701	132,620
Total financial liabilities	2,715,480	2,233,585
Estimated Fair Value | Level 1
Financial assets
Cash and cash equivalents	415,406	437,686
Debt securities, held-to-maturity	0	0
Loans receivable, net of ACL	0	0
Total financial assets	415,406	437,686
Financial liabilities
Term deposits	0	0
FHLB advances	0
Repurchase agreements and other borrowed funds	0	0
Subordinated debentures	0	0
Total financial liabilities	0	0
Estimated Fair Value | Level 2
Financial assets
Cash and cash equivalents	0	0
Debt securities, held-to-maturity	3,459,759	1,220,883
Loans receivable, net of ACL	0	0
Total financial assets	3,459,759	1,220,883
Financial liabilities
Term deposits	970,941	1,040,100
FHLB advances	580,000
Repurchase agreements and other borrowed funds	1,034,397	1,064,888
Subordinated debentures	127,603	131,513
Total financial liabilities	2,712,941	2,236,501
Estimated Fair Value | Level 3
Financial assets
Cash and cash equivalents	0	0
Debt securities, held-to-maturity	0	0
Loans receivable, net of ACL	14,129,375	13,422,898
Total financial assets	14,129,375	13,422,898
Financial liabilities
Term deposits	0	0
FHLB advances	0
Repurchase agreements and other borrowed funds	0	0
Subordinated debentures	0	0
Total financial liabilities	$ 0	$ 0