Commitments and Contingencies Commitments (Details) $ in Thousands	Jun. 30, 2019 USD ($)
Lending related commitments [Line Items]
Unused Commitments to Extend Credit	$ 4,147,149
Standby Letters of Credit [Member]
Lending related commitments [Line Items]
Unused Commitments to Extend Credit	84,731
Unused lines of Credit [Member]
Lending related commitments [Line Items]
Unused Commitments to Extend Credit	2,950,555
Loan Purchase Commitments [Member]
Lending related commitments [Line Items]
Unused Commitments to Extend Credit	660,965
Loan Origination Commitments [Member]
Lending related commitments [Line Items]
Unused Commitments to Extend Credit	$ 450,898