Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Treasury Stock, Common [Member]
Balance at Dec. 31, 2015	$ 12,943,035	$ 205,502	$ 2,923,461	$ (33,338)	$ 9,870,816	$ (23,406)
Net Income (Loss)	(1,096,686)	0	0	0	(1,096,686)	0
Common Stock Issued for the Yates Transaction	2,397,887	252	2,397,635	0	0	0
Common Stock Issued Under Stock Plans	16,397	9	16,388	0	0	0
Dividends, Common Stock	$ (376,012)	0	0	0	(376,012)	0
Common Stock Dividends Declared (in dollars per share)	$ 0.670
Other Comprehensive Income (Loss)	$ 14,328	0	0	14,328	0	0
Change in Treasury Stock - Stock Compensation Plans, Net	(75,226)	0	(27,018)	0	0	(48,208)
Excess Tax Benefit from Stock-Based Compensation	29,357	0	29,357	0	0	0
Restricted Stock and Restricted Stock Units, Net	0	7	(47,509)	0	0	47,502
Stock-Based Compensation Expenses	128,090	0	128,090	0	0	0
Treasury Stock Issued as Compensation	411	0	(19)	0	0	430
Balance at Dec. 31, 2016	13,981,581	205,770	5,420,385	(19,010)	8,398,118	(23,682)
Net Income (Loss)	2,582,579	0	0	0	2,582,579	0
Common Stock Issued Under Stock Plans	7,089	7	7,082	0	0	0
Dividends, Common Stock	$ (387,164)	0	0	0	(387,164)	0
Common Stock Dividends Declared (in dollars per share)	$ 0.670
Other Comprehensive Income (Loss)	$ (287)	0	0	(287)	0	0
Change in Treasury Stock - Stock Compensation Plans, Net	(36,743)	0	(27,348)	0	0	(9,395)
Restricted Stock and Restricted Stock Units, Net	0	11	2,552	0	0	(2,563)
Stock-Based Compensation Expenses	133,849	0	133,849	0	0	0
Treasury Stock Issued as Compensation	2,369	0	27	0	0	2,342
Balance at Dec. 31, 2017	16,283,273	205,788	5,536,547	(19,297)	10,593,533	(33,298)
Net Income (Loss)	3,419,040	0	0	0	3,419,040	0
Common Stock Issued Under Stock Plans	5,620	8	5,612	0	0	0
Dividends, Common Stock	$ (469,443)	0	0	0	(469,443)	0
Common Stock Dividends Declared (in dollars per share)	$ 0.810
Other Comprehensive Income (Loss)	$ 17,939	0	0	17,939	0	0
Change in Treasury Stock - Stock Compensation Plans, Net	(48,454)	0	(35,118)	0	0	(13,336)
Restricted Stock and Restricted Stock Units, Net	0	8	(3,891)	0	0	3,883
Stock-Based Compensation Expenses	155,337	0	155,337	0	0	0
Treasury Stock Issued as Compensation	876	0	307	0	0	569
Balance at Dec. 31, 2018	$ 19,364,188	$ 205,804	$ 5,658,794	$ (1,358)	$ 13,543,130	$ (42,182)