Employee Benefit Plans - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Hour Installment Director	Dec. 31, 2017 USD ($) Director	Dec. 31, 2016 USD ($) Director
401(k) Plan [Abstract]
Minimum age to participate	18 years
Minimum working hours to participate | Hour	20
Annual contribution per employee	100.00%
Employer matching contribution percentage on first 6% of deferred compensation	100.00%
Percent of employee's compensation deferred that receives company match	6.00%
Additional safe harbor contribution by employer, percent	3.00%
401(k) expenses	$ 688,000	$ 685,000	$ 685,000
Deferred Compensation Plan [Abstract]
Number of directors participating in Deferred Compensation Plan | Director	0	0	0
Accrued liability for deferred compensation program	$ 103,000	$ 93,000
Bank-owned life insurance	$ 361	362	$ 361
Maximum [Member]
401(k) Plan [Abstract]
Employer matching contribution	6.00%
Deferred Compensation Plan [Abstract]
Number of installments for contributions | Installment	5
Minimum [Member]
Deferred Compensation Plan [Abstract]
Number of installments for contributions | Installment	1
Former Key Employee [Member]
Deferred Compensation Plan [Abstract]
Deferred compensation expense	$ 44,000	22,000	16,000
Cash surrender value of life insurance policies	1,400	1,300
Bank-owned life insurance	28,000	28,000	25,000
Supplemental Executive Retirement Plan [Member]
Supplemental Executive Retirement Plan [Abstract]
Pension expense	256,000	256,000	311,000
Supplemental Executive Retirement Plan [Member] | Executive [Member]
Supplemental Executive Retirement Plan [Abstract]
Pension expense	$ 35,600	$ 33,000	$ 7,000