Employee Benefit Plans (Details) - 401(k) Employee Savings and Profit Sharing Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Requisite service period	1 year
Company's contribution to the plan	$ 2,797	$ 2,449	$ 2,090