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	Mar. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Fair value of asset derivative instruments	$ 32,501	$ 46,184
Fair value of liability derivative instruments	32,769	46,637
Other Assets [Member] | Interest Rate Lock Commitments
Derivative [Line Items]
Fair value of asset derivative instruments	925	1,096
Other Assets [Member] | Forward Sales Contracts
Derivative [Line Items]
Fair value of asset derivative instruments	505	0
Other Assets [Member] | Interest Rate Swap
Derivative [Line Items]
Fair value of asset derivative instruments	32,501	46,184
Other Liabilities [Member] | Interest Rate Lock Commitments
Derivative [Line Items]
Fair value of liability derivative instruments	0	0
Other Liabilities [Member] | Forward Sales Contracts
Derivative [Line Items]
Fair value of liability derivative instruments	0	165
Other Liabilities [Member] | Interest Rate Swap
Derivative [Line Items]
Fair value of liability derivative instruments	$ 32,769	$ 46,637