Employee Benefit Plans (Additional Information) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
401(k)/Profit Sharing Plan
Contribution match, as a percentage of annual pay	4.00%
Contribution matches, percentage of pre-tax compensation	3.00%	3.00%	3.00%
Expenses under the 401(K)/Profit Sharing plan	$ 2,300	$ 2,200	$ 1,500
Supplemental Executive Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum guaranteed benefit term	15 years
Accumulated benefit obligation	$ 12,300	$ 10,700
Expected amortization of net actuarial loss	$ 561
Supplemental Executive Retirement Plan [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of income replaced	65.00%
Supplemental Executive Retirement Plan [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Percentage of income replaced	75.00%
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected amortization of net actuarial loss	$ 53
Expected amortization of prior service cost	$ 24