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		143,878
Stockholders' Equity Attributable to Parent at Dec. 31, 2012	$ 1,807,333	$ 14,388	$ 335,872	$ 0	$ 1,457,073
Dividends, Cash	(53,546)				(53,546)
Net Income (Loss) Attributable to Parent	217,112				217,112
Stock Issued During Period, Value, Employee Benefit Plan		1,541
Stock Issued During Period, Value, Employee Benefit Plan	33,884	$ 154	33,730
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net	2,358		2,358
Stockholders' Equity Attributable to Parent at Dec. 31, 2013	$ 2,007,141	$ 14,542	$ 371,960	0	1,620,639
Common Stock, Shares, Outstanding		145,419
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	143,486,000	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