Borrowings - Federal Home Loan Bank Advances (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Collateral securing line of credit	$ 2,717,967,000	$ 2,781,606,000
Total borrowing capacity remaining	1,233,254,000	1,276,095,000
Borrowings against line of credit	0	0
Federal Reserve Bank
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Pledged loans to the Federal Reserve Bank	2,440,097,000	2,463,281,000
Line of credit	1,741,192,000	1,695,639,000
Collateral Pledged
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Letter of credit pledged	0	100,000,000
FHLB Overnight
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Additional line available	$ 800,000,000	$ 800,000,000

Amount of advances from the Federal Home Loan Bank (FHLB).

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Amount of advances or credit lines available from the Federal Home Loan Bank (FHLB).

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Amount of the collateral pledged in support of federal home loan bank advances outstanding.

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Amount of maximum advances or credit lines available from the Federal Home Loan Bank (FHLB).

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The sum of the carrying amounts, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of related debt obligations, primarily secured borrowings and repurchase agreements, and for which the transferees are not permitted to sell or re-pledge them to an unrelated party.

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