Interest Expense (Details 3) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Issuance Costs Discussion [Line Items]
Write off debt issuance costs	$ 700		$ 702	$ 1,254	$ 0
Credit agreement
Debt Issuance Costs Discussion [Line Items]
Write off debt issuance costs		$ 1,300
Debt issue costs second amendment		$ 3,600