CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income, Net [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Noncontrolling Interests [Member]	Total
Beginning balance at Dec. 31, 2019	$ 6,547	$ 835,899	$ (37,799)	$ 2,865,939	$ (301,963)	$ 2,969	$ 3,371,592
Beginning balance (in shares) at Dec. 31, 2019	65,472				(5,513)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises	$ 0	26	0	0	$ 327	0	353
Stock option exercises (in shares)	0				15
Issuance of stock for equity awards, net of forfeitures	$ 0	(3,377)	0	0	$ 3,377	0	0
Issuance of stock for equity awards, net of forfeitures (in shares)	0				61
Tax withholdings on equity award vesting	$ 0	0	0	0	$ (3,165)	0	(3,165)
Tax withholdings on equity award vesting (in shares)	0				(38)
Amortization of unearned share-based compensation	$ 0	5,331	0	0	$ 0	0	5,331
Total comprehensive loss, net of taxes	0	0	(1,192)	(347,241)	0	278	(348,155)
Return of investment to noncontrolling interests	0	0	0	0	0	(202)	(202)
Ending balance at Mar. 31, 2020	$ 6,547	837,879	(38,991)	2,518,698	$ (301,424)	3,045	3,025,754
Ending balance (in shares) at Mar. 31, 2020	65,472				(5,475)
Beginning balance at Dec. 31, 2020	$ 6,547	844,979	(61,452)	2,593,393	$ (299,161)	3,247	3,087,553
Beginning balance (in shares) at Dec. 31, 2020	65,472				(5,434)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises	$ 0	19	0	0	$ 392	0	411
Stock option exercises (in shares)	0				8
Issuance of stock for equity awards, net of forfeitures	$ 0	(4,461)	0	0	$ 4,461	0	0
Issuance of stock for equity awards, net of forfeitures (in shares)	0				81
Tax withholdings on equity award vesting	$ 0	0	0	0	$ (2,045)	0	(2,045)
Tax withholdings on equity award vesting (in shares)	0				(39)
Amortization of unearned share-based compensation	$ 0	5,722	0	0	$ 0	0	5,722
Total comprehensive loss, net of taxes	0	0	248	(3,375)	0	255	(2,872)
Return of investment to noncontrolling interests	0	0	0	0	0	(25)	(25)
Ending balance at Mar. 31, 2021	$ 6,547	$ 846,259	$ (61,204)	$ 2,590,018	$ (296,353)	$ 3,477	$ 3,088,744
Ending balance (in shares) at Mar. 31, 2021	65,472				(5,384)