Borrowings and Financing Activities - Schedule of Senior Notes (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Senior notes
Debt Instrument [Line Items]
Total senior notes	$ 1,409,473	$ 1,405,674
Senior notes \| Senior Notes due 2024
Debt Instrument [Line Items]
Total senior notes	446,631	445,512
Senior notes \| Senior Notes due 2025
Debt Instrument [Line Items]
Total senior notes	518,405	516,634
Senior notes \| Senior Notes due 2027
Debt Instrument [Line Items]
Total senior notes	444,437	443,528
FHLB advances
Debt Instrument [Line Items]
FHLB advances due 2021		67,500
FHLB advances due 2022	71,050	61,050
FHLB advances due 2023	52,995	27,995
FHLB advances due 2024	13,954	9,954
FHLB advances due 2025	9,984	9,984
FHLB advances due 2027	3,000	0
Total FHLB advances	$ 150,983	$ 176,483

Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

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