Restricted Cash (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 92,581	$ 89,879	$ 90,593	$ 88,818
Restricted Cash Included in Other Assets	21,105	21,171	21,652	21,883
Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents	$ 113,686	$ 111,050	$ 112,245	$ 110,701
Loss Contingency, Settlement Agreement, Terms	The Company has restricted cash recorded in other assets related to proceeds from an inactive subsidiary of the Company which previously executed separate settlement and release agreements with two of its insurance carriers for $35.0 million. The proceeds of both settlements are restricted and can only be used to pay claims and costs of defense associated with the subsidiary’s asbestos litigation