Derivative Instruments and Hedging Activities - Value of Derivative Assets and Derivative Liabilities (Details) - Not Designated as Hedging Instruments - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Other Assets
Derivatives (included in Other Assets)
Fair value	$ 49,078	$ 78,319
Other Assets | Interest rate swap contracts—commercial loans
Derivatives (included in Other Assets)
Fair value	49,078	78,319
Notional amount	1,003,946	983,638
Collateral posted	0	0
Other Assets | Interest rate lock commitments—mortgage loans
Derivatives (included in Other Assets)
Fair value	1,137	2,900
Notional amount	26,238	51,053
Other Assets | Forward sale contracts—mortgage loans
Derivatives (included in Other Assets)
Fair value	0	0
Notional amount	0	0
Other Liabilities
Derivatives (included in Other Liabilities)
Fair value	49,477	79,033
Other Liabilities | Interest rate swap contracts—commercial loans
Derivatives (included in Other Liabilities)
Fair value	49,477	79,033
Notional amount	1,003,946	983,638
Collateral posted	45,700	77,930
Other Liabilities | Interest rate lock commitments—mortgage loans
Derivatives (included in Other Liabilities)
Fair value	0	0
Notional amount	0	0
Other Liabilities | Forward sale contracts—mortgage loans
Derivatives (included in Other Liabilities)
Fair value	91	385
Notional amount	$ 23,245	$ 47,062