Employee Benefit Plans (Details) - Pension Plan [Member] - 401(k) [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Contribution Plan Disclosure [Line Items]
Company match for defined contribution plan percentage	3.00%
Cost recognized	$ 755	$ 874	$ 1,038