Derivative Instruments and Hedging Activities - Value of Derivative Assets and Derivative Liabilities (Details) - Not Designated as Hedging Instruments - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Other Assets
Derivatives (included in Other Assets)
Fair value	$ 78,319	$ 25,647
Other Assets | Interest Rate Swap Contracts—Commercial Loans
Derivatives (included in Other Assets)
Fair value	78,319	25,647
Notional amount	983,638	740,762
Collateral posted	0	0
Other Assets | Interest Rate Lock Commitments—Mortgage Loans
Derivatives (included in Other Assets)
Fair value	2,900	321
Notional amount	51,053	9,829
Other Assets | Forward Sale Contracts—Mortgage Loans
Derivatives (included in Other Assets)
Fair value	0	1
Notional amount	0	12,750
Other Liabilities
Derivatives (included in Other Liabilities)
Fair value	79,033	25,615
Other Liabilities | Interest Rate Swap Contracts—Commercial Loans
Derivatives (included in Other Liabilities)
Fair value	79,033	25,615
Notional amount	983,638	740,762
Collateral posted	77,930	26,127
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	385	0
Notional amount	$ 47,062	$ 0