Reconciliations of Equity - Reconciliations of Total Equity (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Reconciliations of total equity
Beginning Balance	$ 1,189,913	$ 1,116,738	$ 1,166,065	$ 1,074,193
Issuance of common stock under incentive compensation plan	402	71	1,916	185
Purchase of common stock		(7,041)		(16,976)
Stock-based and deferred compensation	2,077	4,908	(535)	6,925
Net income	12,684	52,126	28,826	96,935
Other comprehensive income (loss)	18,178	(33,619)	35,142	(20,566)
Cash dividends paid:
Common stock	(8,157)	(7,472)	(16,317)	(14,985)
Ending Balance	1,215,097	1,125,711	1,215,097	1,125,711
Common Stock [Member]
Reconciliations of total equity
Beginning Balance	26,958	26,814	26,841	26,761
Issuance of common stock under incentive compensation plan	7	1	33	3
Stock-based and deferred compensation	13	10	104	61
Cash dividends paid:
Ending Balance	26,978	26,825	26,978	26,825
Additional Paid-in Capital [Member]
Reconciliations of total equity
Beginning Balance	239,585	224,500	237,202	220,820
Issuance of common stock under incentive compensation plan	395	70	1,883	182
Stock-based and deferred compensation	2,235	4,940	3,130	8,508
Cash dividends paid:
Ending Balance	242,215	229,510	242,215	229,510
Common Treasury Stock [Member]
Reconciliations of total equity
Beginning Balance	(184,194)	(165,239)	(180,596)	(153,702)
Purchase of common stock		(7,041)		(16,976)
Stock-based and deferred compensation	(171)	(42)	(3,769)	(1,644)
Cash dividends paid:
Ending Balance	(184,365)	(172,322)	(184,365)	(172,322)
Accumulated Other Comprehensive Income (Loss) [Member]
Reconciliations of total equity
Beginning Balance	(150,548)	(140,183)	(167,512)	(153,236)
Other comprehensive income (loss)	18,178	(33,619)	35,142	(20,566)
Cash dividends paid:
Ending Balance	(132,370)	(173,802)	(132,370)	(173,802)
Retained Earnings [Member]
Reconciliations of total equity
Beginning Balance	1,258,112	1,170,846	1,250,130	1,133,550
Net income	12,684	52,126	28,826	96,935
Cash dividends paid:
Common stock	(8,157)	(7,472)	(16,317)	(14,985)
Ending Balance	$ 1,262,639	$ 1,215,500	$ 1,262,639	$ 1,215,500