Shareholders Equity Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]
Common Stock, Shares, Outstanding		282,077
Stockholders' Equity Attributable to Parent at Dec. 31, 2015	$ 2,149,776	$ 28,209	$ 412,931	$ (238,775)	$ 1,947,411
Common Stock Issued to Directors	500,000	4,000	496,000
Dividends, Cash	$ (70,262)				(70,262)
Net Income (Loss) Attributable to Parent	257,491				257,491
Stock Issued During Period, Value, Employee Benefit Plan		3,350
Stock Issued During Period, Value, Employee Benefit Plan	23,018	$ 334	$ 22,684
Treasury Stock, Value, Acquired, Cost Method	(7,658)		11,250	(18,908)
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net	7,346		7,346
Common Stock Issued to Directors Shares		34
Stockholders' Equity Attributable to Parent at Dec. 31, 2016	$ 2,360,211	$ 28,547	$ 454,707	(257,683)	2,134,640
Common Stock, Shares, Outstanding		285,461
Common Stock Issued to Directors	500,000	2,000	498,000
Dividends, Cash	$ (77,712)				(77,712)
Net Income (Loss) Attributable to Parent	399,630				399,630
Stock Issued During Period, Value, Employee Benefit Plan		1,412
Stock Issued During Period, Value, Employee Benefit Plan	39,965	$ 140	$ 39,825
Treasury Stock, Value, Acquired, Cost Method	(139,889)		(11,250)	(128,639)
Common Stock Issued to Directors Shares		22
Stockholders' Equity Attributable to Parent at Dec. 31, 2017	2,582,699	$ 28,689	483,733	(386,322)	2,456,599
Stockholders' Equity Attributable to Parent (Accounting Standards Update 2014-09 [Member]) at Dec. 31, 2017	$ 2,700,214	$ 28,689	483,733	(386,322)	2,574,114
Cumulative Effect of New Accounting Principle in Period of Adoption | Accounting Standards Update 2014-09 [Member]					117,515
Common Stock, Shares, Outstanding	276,210,910	286,895
Common Stock, Shares, Outstanding | Accounting Standards Update 2014-09 [Member]		286,895
Net Unrealized Holding Gain on Available for Sale Securities	$ (6)		$ (47)		41
Common Stock Issued to Directors	700,000	1,000	699,000
Dividends, Cash	$ (84,690)				(84,690)
Net Income (Loss) Attributable to Parent	344,255				344,255
Stock Issued During Period, Value, Employee Benefit Plan		3,096
Stock Issued During Period, Value, Employee Benefit Plan	40,167	$ 310	$ 39,857
Stock Issued During Period, Shares, Acquisitions		3,376
Stock Issued During Period, Value, Acquisitions	100,000	$ 338	99,662
Treasury Stock, Value, Acquired, Cost Method	(100,000)		(8,750)	(91,250)
Common Stock Issued to Directors Shares		13
Stockholders' Equity Attributable to Parent at Dec. 31, 2018	$ 3,000,568	$ 29,338	615,180	$ (477,572)	2,833,622
Common Stock, Shares, Outstanding	279,583,006	293,380
Net Unrealized Holding Gain on Available for Sale Securities	$ (78)		$ (21)		$ (57)