Goodwill and Intangible Assets - Narrative (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Goodwill	$ 458,472	$ 437,935
Weighted average amortization period	4 years 6 months
Specialty Building Products
Segment Reporting Information [Line Items]
Goodwill	$ 450,900	432,600
Mechanical Insulation
Segment Reporting Information [Line Items]
Goodwill	$ 7,600	$ 5,300