Commitments and Contingencies Commitments (Details) $ in Thousands	Sep. 30, 2021 USD ($)
Lending related commitments [Line Items]
Unused Commitments to Extend Credit	$ 4,426,188
Commitments to fund loans
Lending related commitments [Line Items]
Unused Commitments to Extend Credit	401,167
Unfunded commitments under lines of credit
Lending related commitments [Line Items]
Unused Commitments to Extend Credit	3,925,811
Commercial and standby letters of credit
Lending related commitments [Line Items]
Unused Commitments to Extend Credit	$ 99,210