Pension, Other Postretirement Benefits and Employee Savings and Investment Plans (Additional Information) (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Projected benefit obligation of plan with accumulated benefit obligation in excess of plan assets		$ 200,000	$ 155,800,000
Accumulated benefit obligation of plan with accumulated benefit obligation in excess of plan assets		200,000	155,800,000
Fair value of the plan assets of plan with accumulated benefit obligation in excess of plan assets		0	147,100,000
Projected benefit obligation of plan with plan assets in excess of accumulated benefit obligation		172,400,000	30,000,000
Accumulated benefit obligation of plan with plan assets in excess of accumulated benefit obligation		172,400,000	30,000,000
Fair value of the plan assets of plan with plan assets in excess of accumulated benefit obligation		$ 191,700,000	33,000,000
Health care cost, employees age		65 years
Health care cost trend rate annual change		0.25%
Percentage point change in assumed health care cost trend rates		1.00%
Historical return on plan assets over 20 years		7.05%
Anticipated payment for defined benefit pensions	$ 25,000,000	$ 25,354,000	$ 906,000	$ 842,000
Document Fiscal Year Focus		2018
Retirees of 65 Years Old or Younger
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Health care cost trend rate assumed for next fiscal year		7.00%	7.25%
Ultimate health care cost trend rate		4.50%
Retirees of 65 Years Old or Older
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Health care cost trend rate assumed for next fiscal year		7.00%	7.25%
Ultimate health care cost trend rate		4.50%
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss to be recognized over next twelve months		$ 1,800,000
Expected long-term rate of return on plan assets		4.69%
Required employer contribution			$ 400,000
Employer contributions		$ 25,000,000	$ 372,000
Pension Benefits | Equity Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan asset allocations		1.00%	4.00%
Pension Benefits | Debt Securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan asset allocations		99.00%	96.00%
Retirement Health and Life Insurance Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss to be recognized over next twelve months		$ 1,000,000
Employer contributions		364,000	$ 533,000
Rogers Employee Savings and Investment Plan (RESIP)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
IRS deferral limit		$ 18,500
Employee compensation subject to employer matching percent		6.00%
Employer contributions		$ 5,600,000	$ 4,000,000	$ 3,000,000
Rogers Employee Savings and Investment Plan (RESIP) | 100% match
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employee compensation subject to employer matching percent		3.50%
Rogers Employee Savings and Investment Plan (RESIP) | 100% match | 1% of compensation
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employee compensation subject to employer matching percent		1.00%
Employer matching contribution percent		100.00%
Rogers Employee Savings and Investment Plan (RESIP) | 50% match | 5% of compensation
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employee compensation subject to employer matching percent		5.00%
Employer matching contribution percent		50.00%
DeWAL Industries, Inc 401k Profit Sharing Plan (DeWAL Plan)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employee compensation subject to employer matching percent		3.00%
Employer matching contribution, percent of match		100.00%