Derivative Financial Instruments and Hedging Table of Derivatives - Gross notional and fair value amounts of derivatives (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional values	$ 292,860	$ 458,797
Asset derivatives	3,504	5,013
Liability derivatives	876	117
Interest Risk, Interest Rate Lock Commitments
Derivative [Line Items]
Notional values	122,477	190,645
Asset derivatives	3,460	4,808
Liability derivatives	0	0
Interest Risk, Forward Delivery Contracts
Derivative [Line Items]
Notional values	41,383	71,152
Asset derivatives	5	30
Liability derivatives	52	0
Interest Risk, TBA Mortgage Backed Securities
Derivative [Line Items]
Notional values	129,000	197,000
Asset derivatives	39	175
Liability derivatives	$ 824	$ 117