Employee Benefit Plans - Defined Benefit Plans - Components of Periodic Pension Costs (Details) - USD ($)		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other changes in plan assets and benefit obligations recognized in other comprehensive loss
Amortization of prior service cost arising during the period	[1]	$ 60,000	$ 61,000	$ 68,000
Total recognized in accumulated other comprehensive income (loss)		123,000	513,000	1,400,000
The Bank | Cash Balance Plan
Components of net periodic benefit cost
Service cost		1,076,000	1,040,000	763,000
Interest cost		528,000	468,000	451,000
Expected return on plan assets		(1,045,000)	(1,043,000)	(832,000)
Amortization of prior service cost		(61,000)	(61,000)	(68,000)
Recognized net actuarial loss		158,000	130,000	33,000
Net periodic benefit cost		656,000	534,000	347,000
Other changes in plan assets and benefit obligations recognized in other comprehensive loss
Net loss		129,000	602,000	2,048,000
Prior service cost			126,000
Amortization of prior service cost arising during the period		60,000	61,000	68,000
Deferred taxes		(66,000)	(276,000)	(741,000)
Total recognized in accumulated other comprehensive income (loss)		123,000	513,000	1,375,000
Total recognized in net periodic benefit cost and other comprehensive loss (income )		$ 779,000	$ 1,047,000	$ 1,722,000

[1] These items are included in the computation of net periodic benefit cost, which is a component of “Salaries and employee benefits” on the consolidated statements of income. See Note 12, Employee Benefit Plans, for additional information.