Stockholders' Equity - Stock Option Activities of Long-Term Incentive and Option Plans (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2016
Stockholders Equity [Line Items]
Shares outstanding at beginning of year	124,000
Cancelled, forfeited or expired, Shares	(2,000)
Shares outstanding at end of year	122,000	124,000
Shares exercisable at end of year	122,000
Outstanding at beginning of year, Weighted-Average Exercise Price	$ 33.86
Forfeited or expired, Weighted-Average Exercise Price	34.50
Outstanding at end of year, Weighted-Average Exercise Price	33.85	$ 33.86
Exercisable at end of year, Weighted-Average Exercise Price	$ 33.85
Stock-based compensation expense - Cost of sales	$ 106,000	$ 122,000	$ 141,000
Stock-based compensation expense - SG&A	42,000	50,000	71,000
Income tax benefit	(36,000)	(42,000)	(54,000)
Total fair value of options vested during the year	$ 180,000	$ 169,000	$ 169,000
Total weighted-average remaining vesting period in years	0 years	5 months 26 days	1 year 18 days
Total weighted-average remaining contractual life period in years (options outstanding)	2 years 7 months 20 days	3 years 7 months 9 days	4 years 7 months 9 days
Total weighted-average remaining contractual life period in years (options exercisable)	2 years 7 months 20 days	3 years 5 months 19 days	4 years 3 months 21 days
2016 Plan [Member]
Stockholders Equity [Line Items]
Granted, Shares	0	0	0
Maximum number of securities for issuance	2,750,000
Number of awards available to be granted	1,016,951			2,750,000
2016 Plan [Member] | Restricted Stock/Performance-Based Restricted Stock/Restricted Stock Units [Member]
Stockholders Equity [Line Items]
Number of unvested restricted stock/performance-based restricted stock/restricted stock units outstanding	1,169,527
2008 Plan [Member]
Stockholders Equity [Line Items]
Shares outstanding at end of year	122,000
Shares exercisable at end of year	122,000