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		145,419
Stockholders' Equity Attributable to Parent at Dec. 31, 2013	$ 2,007,141	$ 14,542	$ 371,960	$ 0	$ 1,620,639
Common Stock Issued to Directors	320,000	1,000	319,000
Dividends, Cash	$ (59,334)				(59,334)
Net Income (Loss) Attributable to Parent	206,896				206,896
Stock Issued During Period, Value, Employee Benefit Plan		442
Stock Issued During Period, Value, Employee Benefit Plan	30,449	$ 44	$ 30,405
Treasury Stock, Value, Acquired, Cost Method	(75,025)			(75,025)
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net	3,298		3,298
Common Stock Issued to Directors Shares		10
Stockholders' Equity Attributable to Parent at Dec. 31, 2014	$ 2,113,745	$ 14,587	$ 405,982	(75,025)	1,768,201
Common Stock, Shares, Outstanding		145,871
Common Stock Issued to Directors	500,000	2,000	498,000
Dividends, Cash	$ (64,108)				(64,108)
Net Income (Loss) Attributable to Parent	243,318				243,318
Stock Issued During Period, Value, Employee Benefit Plan		528
Stock Issued During Period, Value, Employee Benefit Plan	28,045	$ 53	$ 27,992
Treasury Stock, Value, Acquired, Cost Method	(175,000)		(11,250)	(163,750)
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net	3,276		3,276
Common Stock Issued to Directors Shares		16
Stockholders' Equity Attributable to Parent at Dec. 31, 2015	$ 2,149,776	$ 14,642	$ 426,498	(238,775)	1,947,411
Common Stock, Shares, Outstanding	138,985,000	146,415
Common Stock Issued to Directors	500,000	2,000	498,000
Dividends, Cash	$ (70,262)				(70,262)
Net Income (Loss) Attributable to Parent	257,491				257,491
Stock Issued During Period, Value, Employee Benefit Plan		1,675
Stock Issued During Period, Value, Employee Benefit Plan	23,018	$ 167	$ 22,851
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		17
Stockholders' Equity Attributable to Parent at Dec. 31, 2016	$ 2,360,211	$ 14,811	$ 468,443	$ (257,683)	$ 2,134,640
Common Stock, Shares, Outstanding	140,104,000	148,107