Acquisitions - Identifiable Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Aug. 31, 2018
Business Acquisition [Line Items]
Goodwill (Note 5)	$ 197,022	$ 196,963
Interface
Business Acquisition [Line Items]
Accounts receivable			$ 25,182
Inventories			17,313
Prepaid expenses and other current assets			2,382
Property, plant and equipment			40,902
Goodwill (Note 5)			130,991
Other intangible assets (Note 5)			106,900
Other assets			308
Total assets acquired, net of cash acquired			323,978
Current liabilities			(11,319)
Deferred tax liabilities			(24,904)
Benefit plan liabilities (Note 12)			(18,352)
Other long-term liabilities			(1,031)
Total liabilities assumed			(55,606)
Total purchase price, net of cash acquired			$ 268,372