Capital Stock - Summary of Common Stock Activity (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balances (in shares)	(38,841,194)
Stock options exercised (in shares)	274,704	198,535	215,724
Stock options forfeitures, Shares		(95)	(4,721)
Ending Balances (in shares)	(39,067,902)	(38,841,194)
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balances (in shares)	(62,081,391)	(62,081,391)	(62,081,391)
Ending Balances (in shares)	(62,081,391)	(62,081,391)	(62,081,391)
Beginning Balances	$ (229,127)	$ (211,806)	$ (194,953)
Ending Balances	$ (242,693)	$ (229,127)	$ (211,806)
Treasury
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balances (in shares)	(23,240,197)	(23,554,868)	(23,858,463)
Ending Balances (in shares)	(23,013,489)	(23,240,197)	(23,554,868)
Beginning Balances	$ (303,566)	$ (296,390)	$ (296,081)
Ending Balances	$ (326,156)	$ (303,566)	$ (296,390)
Restricted Stock | Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock awards (in shares)	0	0	0
Restricted stock expense (in shares)	0	0	0
Restricted stock forfeitures (in shares)	0	0	0
Restricted stock awards	$ (773)	$ (1,253)	$ (1,079)
Share-based compensation expense	7,065	7,397	6,504
Stock compensation awards forfeited, Value	$ (807)	$ (483)	$ (283)
Restricted Stock | Treasury
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock awards (in shares)	55,691	96,893	92,401
Restricted stock expense (in shares)	0	0	0
Restricted stock forfeitures (in shares)	0	0	0
Restricted stock awards	$ (773)	$ (1,253)	$ (1,079)
Share-based compensation expense	0	0	0
Stock compensation awards forfeited, Value	$ 0	$ 0
Stock Options | Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock expense (in shares)	0	0
Stock options exercised (in shares)	0	0	0
Stock options forfeitures, Shares	0	0	0
Share-based compensation expense	$ 153	$ 492	$ 272
Stock compensation awards forfeited, Value	(40)	(5)	(55)
Stock options exercised	$ 8,590	$ 5,107	$ 5,738
Stock Options | Treasury
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock expense (in shares)	0	0	0
Stock options exercised (in shares)	274,672	193,681	215,724
Stock options forfeitures, Shares	0	0	0
Share-based compensation expense	$ 0	$ 0	$ 0
Stock compensation awards forfeited, Value	0	0	0
Stock options exercised	$ 3,856	$ 2,364	$ 2,835
Performance Stock | Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock expense (in shares)	0	0	0
Restricted stock forfeitures (in shares)	0	0
Performance stock issued (in shares)	0	0	0
Share-based compensation expense	$ 1,305	$ 6,574	$ 6,186
Stock compensation awards forfeited, Value	(755)	$ (215)	(385)
Stock Issued During Period, Shares, Acquisitions		0
Performance stock issued	$ (1,826)	$ (1,778)	$ (523)
Stock Issued During Period, Value, Acquisitions		$ 921
Performance Stock | Treasury
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock expense (in shares)	0	0	0
Restricted stock forfeitures (in shares)	0	0	0
Performance stock issued (in shares)	134,824	139,478	41,660
Share-based compensation expense	$ 0	$ 0	$ 0
Stock compensation awards forfeited, Value	0	$ 0	0
Stock Issued During Period, Shares, Acquisitions		0
Performance stock issued	$ (1,826)	$ (1,778)	$ (523)
Stock Issued During Period, Value, Acquisitions		$ 0
Employee Stock Purchase Plan | Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock purchase plan (in shares)	0	0	0
Employee stock purchase plan	$ 654	$ 564	$ 478
Employee Stock Purchase Plan | Treasury
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee stock purchase plan (in shares)	6,494	5,895	7,725
Employee stock purchase plan	$ 93	$ 77	$ 78
Stock Compensation Plan | Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares purchased (in shares)	0	0	0
Treasury shares purchased for stock compensation programs	$ 0	$ 0	$ 0
Stock Compensation Plan | Treasury
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares purchased (in shares)	(69,973)	(87,811)	(53,915)
Treasury shares purchased for stock compensation programs	$ (9,025)	$ (9,301)	$ (4,824)
Share Repurchase Program, May 2015 | Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares purchased (in shares)	0	0
Treasury shares purchased for stock compensation programs	$ 0	$ 0
Share Repurchase Program, May 2015 | Treasury
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares purchased (in shares)	(175,000)	(33,465)
Treasury shares purchased for stock compensation programs	$ (20,113)	$ (3,347)
Share Repurchase Program, May 2015 | Treasury
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares purchased (in shares)	(175,000)	(33,465)	0