CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (UNAUDITED) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings
Beginning Balance, Value at Dec. 31, 2018	$ 3,000,568	$ 29,338	$ 615,180	$ (477,572)	$ 2,833,622
Beginning Balance, Shares at Dec. 31, 2018		293,380
Net income	113,896				113,896
Net unrealized holding (loss) gain on available-for- sale securities	106		106
Common stock issued for employee stock benefit plans	6,209	$ 246	5,963
Common stock issued for employee stock benefit plans, Shares		2,465
Cash dividends paid	(22,348)				(22,348)
Ending Balance, Value at Mar. 31, 2019	3,098,431	$ 29,584	621,249	(477,572)	2,925,170
Ending Balance, Shares at Mar. 31, 2019		295,845
Beginning Balance, Value at Dec. 31, 2019	$ 3,350,279	$ 29,711	716,049	(536,243)	3,140,762
Beginning Balance, Shares at Dec. 31, 2019	281,655	297,106
Net income	$ 152,400				152,400
Net unrealized holding (loss) gain on available-for- sale securities	293		194		99
Common stock issued for employee stock benefit plans	2,200	$ 182	2,018
Common stock issued for employee stock benefit plans, Shares		1,828
Purchase of treasury stock	(1,429)			(1,429)
Cash dividends paid	(23,902)				(23,902)
Ending Balance, Value at Mar. 31, 2020	$ 3,479,841	$ 29,893	$ 718,261	$ (537,672)	$ 3,269,359
Ending Balance, Shares at Mar. 31, 2020	283,441	298,934