Restricted Cash (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 128,161	$ 104,147	$ 99,810	$ 89,879
Restricted Cash Included in other current assets	460	0	0	0
Restricted Cash Included in other assets	19,839	20,278	20,594	21,171
Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents	$ 148,460	$ 124,425	$ 120,404	$ 111,050
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 an original total value of $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. The proceeds of the settlement and release agreements have been deposited into interest bearing accounts that earned $0.2 million in the nine months ended September 30, 2019 compared to $0.1 in the nine months ended September 30, 2018. The interest was offset by $0.6 million of payments during the nine months ended September 30, 2019 compared to $0.7 million in the nine months ended September 30, 2018. Due to the restricted nature of the proceeds, a corresponding deferred credit was established in other non-current liabilities for an equal and offsetting amount, and will remain until the restrictions lapse or the funds are exhausted via payments of claims and costs of defense