Employer Sponsored Benefit Plans - Narrative (Details) - USD ($)	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Interface
Defined Benefit Plan Disclosure [Line Items]
Contributions made by company to domestic pension plan	$ 300,000			$ 1,100,000
Expected employer contributions during remainder of fiscal year	1,500,000			1,500,000
United States | Pension plan
Defined Benefit Plan Disclosure [Line Items]
Pre-tax settlement loss	200,000	$ 25,500,000
Contributions made by company to domestic pension plan	$ 0		$ 3,000,000.0	$ 0	$ 7,200,000