Employer Sponsored Benefit Plans - Narrative (Details) $ in Thousands	4 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($) plan_participant active_employee	Dec. 31, 2018 USD ($) plan_participant active_employee	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Aug. 31, 2018 USD ($)	Jan. 01, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Future amortization of gain (loss)	$ (500)	$ (500)
Cumulative effect recognized on initial application of the new guidance	$ 411,325	411,325	$ 374,783			$ 376,381
Selling, product development and administrative expenses		$ 103,457	$ 97,159	$ 83,359
Expected return on plan assets, benefit obligation (as a percent)	4.08%	4.08%	5.80%
Defined Contribution Plan:
Employer Contributions to 401(k) Plan		$ 2,900	$ 2,600	2,500
Matching contribution of employees' gross pay (as a percent)		5.00%
Matching contribution of employees' gross pay, first 3% (as a percent)		100.00%
Matching contribution of employees' gross pay, remaining 2% (as a percent)		50.00%
Minimum
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions in next fiscal year	$ 3,500	$ 3,500
Maximum
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions in next fiscal year	5,500	5,500
United States
Defined Benefit Plan Disclosure [Line Items]
Funded (unfunded) status of plan	(15,227)	(15,227)	(7,708)
Pension plan liability	15,227	15,227	7,708
Accumulated other comprehensive loss, net of tax	21,850	21,850	17,632
Increase in OCI pension adjustment		1,800	2,100
United States | Minimum
Defined Benefit Plan Disclosure [Line Items]
Future amortization of gain (loss)	(29,000)	(29,000)
United States | Maximum
Defined Benefit Plan Disclosure [Line Items]
Future amortization of gain (loss)	(33,000)	(33,000)
Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan liability	4,700	4,700	1,900
Accumulated other comprehensive loss, net of tax	400	400	400
Accounting Standards Update 2017-07
Defined Benefit Plan Disclosure [Line Items]
Cumulative effect recognized on initial application of the new guidance			300	300
Selling, product development and administrative expenses			$ 500	$ 400
Interface
Defined Benefit Plan Disclosure [Line Items]
Funded (unfunded) status of plan					$ (11,200)
Interface | United States
Defined Benefit Plan Disclosure [Line Items]
Increase in OCI pension adjustment		1,800
Postemployment Retirement Benefits | Interface | United States
Defined Benefit Plan Disclosure [Line Items]
Pension plan liability	4,100	$ 4,100			4,100
Benefit expense since acquisition date	100
Benefit payments since acquisition date	$ 100
Pension Plan | United States
Defined Benefit Plan Disclosure [Line Items]
Number of plan participants | plan_participant	900	900
Number of active employee plan participants | active_employee	200	200
Pension Plan | United States | Minimum
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions in next fiscal year	$ 2,000	$ 2,000
Pension Plan | United States | Maximum
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions in next fiscal year	$ 4,000	$ 4,000
Pension Plan | Interface | Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan liability					$ 2,900