Consolidated Statement of Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Capital in Excess of Par Value	Retained Earnings [Member]	Accumulated Other Comprehensive Income	Noncontrolling Interest
Balance at beginning of period at Dec. 31, 2019	$ 1,823,255	$ 185,101	$ (3,916)	$ 1,010,361	$ 601,903	$ 29,864	$ (58)
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Comprehensive income	50,799	0	0	0	81,941	(31,200)	58
Dividends, Common Stock	$ (34,414)	0	0	0	34,414	0	0
Dividends declared per share	$ 190
Stock option exercises	$ 15,126	789	0	14,337	0	0	0
Restricted stock awards, net of forfeitures	0	168	0	(168)	0	0	0
Employee share-based compensation earned	3,406	0	0	3,406	0	0	0
Purchase of Company common stock	(123,102)	0	(2,901)	(16,202)	(103,999)	0	0
Other	(1,095)	0	0	(1,095)	0	0	0
Balance at end of period at Mar. 31, 2020	1,751,093	186,058	(6,817)	1,010,639	562,549	(1,336)	0
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Stockholders' Equity, Period Increase (Decrease) | Accounting Standards Update 2016-13 [Member]	17,118	0	0	0	17,118	0	0
Balance at beginning of period at Dec. 31, 2020	1,752,621	$ 174,792	$ (4,075)	$ 981,934	$ 560,731	$ 39,366	$ (127)
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Comprehensive income	$ 233,960
Dividends declared per share	$ 210
Treasury Stock, Shares, Retired	0	(3,000)	(3,000)	0	0	0	0
Balance at end of period at Mar. 31, 2021	$ 1,850,660	$ 175,051	$ (6,214)	$ 975,232	$ 662,271	$ 44,371	$ (51)