Mortgage Banking (Additional Information) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Servicing Assets at Fair Value [Line Items]
Gain (Loss) on Sale of Mortgage Loans		$ 6,256,000	$ 6,201,000	$ 1,278,000
Receivables Held-for-sale, Amount		8,100,000	15,100,000
Unrealized Gain (Loss) on Derivatives		37,000	(289,000)
Unrealized gain (loss) on loans held for sale		326,000	(422,000)	133,000
Servicing Asset at Amortized Cost		1,025,000	1,210,000	2,161,000	$ 493,000
Servicing Asset at Amortized Cost		$ 1,025,000	$ 1,210,000	2,161,000	$ 493,000
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Prepayment Speed		14.00%	14.60%
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate		11.20%	7.80%
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 10 Percent Adverse Change in Prepayment Speed		$ 76,000
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 20 Percent Adverse Change in Prepayment Speed		148,000
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 10 Percent Adverse Change in Discount Rate		54,000
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 20 Percent Adverse Change in Discount Rate		105,000
Advance Payments by Borrowers for Taxes and Insurance		194,000	$ 2,000,000
Capitalized servicing right fees upon sale(1)	[1]	22,000	9,000	294,000
Fixed Rate Residential Mortgage [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage Loans on Real Estate, Cost of Mortgages Sold		218,600,000	232,200,000	61,200,000
Custodial escrow balances		4,200,000	11,900,000
Accounts Receivable, Net		58,000	2,700,000
Allowance for Doubtful Accounts Receivable		0	829,000
SBM Financial, Inc. [Member]
Servicing Assets at Fair Value [Line Items]
Capitalized servicing right fees upon sale(1)		0	0	1,608,000
Forward Contracts [Member]
Servicing Assets at Fair Value [Line Items]
Unrealized Gain (Loss) on Derivatives		(136,000)	278,000	0
Servicing Assets [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage loans serviced during period, value		275,200,000	332,700,000
Fees and Commissions, Mortgage Banking and Servicing		1,000,000	1,100,000	597,000
Sub-Serviced Loans [Member]
Servicing Assets at Fair Value [Line Items]
Mortgage loans serviced during period, value		349,700,000	930,800,000
Fees and Commissions, Mortgage Banking and Servicing		$ 12,000	$ 1,700,000	$ 1,200,000

[1] Reported within mortgage banking income, net on the Company's consolidated statements of income.