Employee Benefit Plans (Detail Textuals 1) - Supplemental Retirement Plan ('SERP') - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Variable life insurance policies investment amount	$ 51,000,000	$ 47,700,000
Fair value of plan assets	23,463,000	18,367,000
Trading (losses) gains related to the SERP assets	$ 3,156,000	$ 966,000	$ (519,000)