Earnings per Share - Composition of Weighted-Average Common Shares (Denominator) Used in Basic and Diluted Earnings Per Share (Detail) - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Weighted Average Number of Shares Issued, Basic	113,914,902	113,914,902
Average treasury shares (in shares)	(15,672,850)	(15,291,253)
Weighted Average Number of Shares, Deferred Compensation Plans	(38,453)	(37,411)
Average unearned nonvested shares	(79,972)	(107,197)
Weighted average common shares and common stock equivalents used to calculate basic earnings per share (in shares)	98,123,627	98,479,041
Additional common stock equivalents (nonvested stock) used to calculate diluted earnings per share	196,441	190,375
Weighted Average Number Of Additional Shares Deferred Compensation Plan	41,426	37,411
Weighted average common shares and common stock equivalents used to calculate diluted earnings per share (in shares)	98,361,494	98,706,827
Basic Earnings per Share (in dollars per share)	$ 0.05	$ 0.25
Diluted Earnings per Share (in dollars per share)	$ 0.05	$ 0.25