Deferred Compensation Benefits - Schedule of Accrued Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
ESBP [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liabilities	$ 581	$ 659
Non-current liabilities	$ 4,596	$ 5,750
Benefit obligation	3.76%	3.06%
Net periodic pension cost	3.06%	3.41%
NDBP [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current liabilities	$ 4,747	$ 5,495
Benefit obligation	1.90%	1.80%
Net periodic pension cost	1.80%	1.30%
Expected return on plan assets	4.00%	4.00%
BDBP [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current assets	$ 92	$ 96
Benefit obligation	1.75%	1.62%
Net periodic pension cost	1.65%	1.65%
Salary increase rate	1.80%	1.80%
Expected return on plan assets	3.25%	3.25%
FDBP [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current liabilities	$ 363
Benefit obligation	1.60%
Net periodic pension cost	1.45%
Salary increase rate	1.75%