Derivatives and Balance Sheet Offsetting - Fair value of derivatives & classifications table (Details) - Not Designated as Hedging Instrument [Member] - Interest Rate Contracts [Member] - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Fair value of asset derivative instruments	$ 29,139	$ 46,184
Fair value of liability derivative instruments	29,139	46,637
Other Assets [Member] | Interest Rate Lock Commitments Contracts
Derivative [Line Items]
Fair value of asset derivative instruments	482	1,096
Other Assets [Member] | Interest rate Forward Sales Contracts
Derivative [Line Items]
Fair value of asset derivative instruments	0	0
Other Assets [Member] | Interest Rate Swap Contracts
Derivative [Line Items]
Fair value of asset derivative instruments	29,139	46,184
Other Liabilities [Member] | Interest Rate Lock Commitments Contracts
Derivative [Line Items]
Fair value of liability derivative instruments	0	0
Other Liabilities [Member] | Interest rate Forward Sales Contracts
Derivative [Line Items]
Fair value of liability derivative instruments	79	165
Other Liabilities [Member] | Interest Rate Swap Contracts
Derivative [Line Items]
Fair value of liability derivative instruments	$ 29,139	$ 46,637