Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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Derivative Financial Instruments (Details) - USD ($)	3 Months Ended		6 Months Ended
Derivative Financial Instruments (Details) - USD ($)	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2009
Derivative Financial Instruments
Notional amount	$ 826,004,000	$ 247,283,000	$ 826,004,000	$ 247,283,000
Estimated fair value gain			8,848,000	1,874,000
Estimated fair value loss			8,097,000	592,000
Gain or loss recorded	0	0	$ 0	0
Variable rate basis, variable rate receivable on notional amount			three-month LIBOR
Estimated gain (loss) on fair value of open contracts related to mortgage servicing rights			$ 291,000	9,000
After-tax unrealized gain on cash flow hedge in other comprehensive income	37,000	23,000	102,000	67,000
Cash flow hedge liability	116,000	389,000	116,000	389,000
Ineffectiveness in the cash flow hedge	0	0	0	0
Collateral provided	300,000	450,000	300,000	450,000
Interest Rate Derivative Assets, at Fair Value	7,700,000		7,700,000
Interest Rate Derivative Liabilities, at Fair Value	7,900,000		7,900,000
Interest Rate Derivatives, at Fair Value, Net	240,000	203,000	240,000	203,000
Other Assets.
Derivative Financial Instruments
Interest Rate Derivative Assets, at Fair Value		208,000		208,000
Other Liabilities.
Derivative Financial Instruments
Interest Rate Derivative Liabilities, at Fair Value		203,000		203,000
Mortgage loan pipeline
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Obligation	89,085,000	115,820,000	89,085,000	115,820,000	$ 71,477,000
Expected closures
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Obligation	66,813,000	86,865,000	66,813,000	86,865,000	53,608,000
Interest rate contracts
Derivative Financial Instruments
Notional amount	654,100,000	27,300,000	654,100,000	27,300,000
Fair value of non-designated interest rate swaps recorded in other assets and other liabilities		5,000		5,000
Interest rate contracts \| LIBOR
Derivative Financial Instruments
Notional amount	$ 8,000,000		$ 8,000,000
Interest rate contracts \| Cash flow hedge
Derivative Financial Instruments
Notional amount						$ 8,000,000
Interest rate contracts \| Cash flow hedge \| LIBOR
Derivative Financial Instruments
Fixed rate payable on notional amount (as a percent)	4.06%		4.06%
Fixed interest rate on interest rate swap (as a percent)	4.06%		4.06%
Mortgage servicing rights hedging \| Non-designated hedges
Derivative Financial Instruments
Notional amount	$ 63,500,000	102,500,000	$ 63,500,000	102,500,000
Mortgage servicing rights hedging \| Non-designated hedges \| Other Assets.
Derivative Financial Instruments
Notional amount	63,500,000	102,500,000	63,500,000	102,500,000
Estimated fair value gain			291,000	9,000
Mortgage loan pipeline commitments
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Obligation	1,159,000	1,568,000	1,159,000	1,568,000	920,000
Forward sales commitments
Obligation under forward commitments, the fair value of those obligations along with the fair value of derivative instruments associated with forward commitments
Obligation	92,584,000	109,525,000	92,584,000	109,525,000	89,317,000
Fair value of forward commitments	352,000	(89,000)	352,000	(89,000)	$ (19,000)
Forward sales commitments \| Non-designated hedges \| Other Assets.
Derivative Financial Instruments
Notional amount	92,584,000	109,525,000	92,584,000	109,525,000
Estimated fair value gain			807,000	1,657,000
Interest rate swap \| Cash flow hedge \| Other Liabilities. \| Counterparty
Derivative Financial Instruments
Notional amount	8,000,000	8,000,000	8,000,000	8,000,000
Estimated fair value loss			116,000	389,000
Interest rate swap \| Fair Value Hedging \| Other Assets. \| Counterparty
Derivative Financial Instruments
Notional amount	2,824,000		2,824,000
Estimated fair value gain			8,000
Interest rate swap \| Non-designated hedges \| Other Assets and Other Liabilities \| Borrower
Derivative Financial Instruments
Notional amount	327,027,000	13,629,000	327,027,000	13,629,000
Estimated fair value gain			437,000	208,000
Estimated fair value loss			7,947,000
Interest rate swap \| Non-designated hedges \| Other Assets and Other Liabilities \| Counterparty
Derivative Financial Instruments
Notional amount	327,027,000	$ 13,629,000	327,027,000	13,629,000
Estimated fair value gain			7,271,000
Estimated fair value loss				$ 203,000
Foreign exchange contract
Derivative Financial Instruments
Notional amount	2,500,000		2,500,000
Foreign exchange contract \| Non-designated hedges \| Other Assets and Other Liabilities \| Borrower
Derivative Financial Instruments
Notional amount	2,521,000		2,521,000
Estimated fair value loss			34,000
Foreign exchange contract \| Non-designated hedges \| Other Assets and Other Liabilities \| Counterparty
Derivative Financial Instruments
Notional amount	$ 2,521,000		2,521,000
Estimated fair value gain			$ 34,000