Consolidated Statements Of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2012	$ 1,560,360	$ 2,966	$ 61,436	$ 1,477,601	$ 18,357
Balance (in shares) at Dec. 31, 2012		296,564,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends paid in cash	(237,456)			(237,456)
Purchases of common stock	(9,080)	$ (2)	(9,078)	0
Purchases of common stock (in shares)		(200,000)
Stock options exercised	9,306	$ 4	9,302
Stock options exercised (in shares)		389,000
Stock-based compensation	5,400		5,400
Excess tax benefits from stock-based compensation	2,787		2,787
Net earnings	448,636			448,636
Other comprehensive income (loss)	(7,256)				(7,256)
Balance at Dec. 31, 2013	1,772,697	$ 2,968	69,847	1,688,781	11,101
Balance (in shares) at Dec. 31, 2013		296,753,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends paid in cash	(296,581)			(296,581)
Purchases of common stock	(52,942)	$ (12)	(52,930)	0
Purchases of common stock (in shares)		(1,200,000)
Stock options exercised	7,697	$ 3	7,694
Stock options exercised (in shares)		315,000
Stock-based compensation	7,039		7,039
Excess tax benefits from stock-based compensation	2,094		2,094
Net earnings	494,150			494,150
Other comprehensive income (loss)	(18,937)				(18,937)
Balance at Dec. 31, 2014	$ 1,915,217	$ 2,959	33,744	1,886,350	(7,836)
Balance (in shares) at Dec. 31, 2014	295,867,844	295,868,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends paid in cash	$ (327,101)			(327,101)
Purchases of common stock	(292,951)	$ (71)	(60,042)	(232,838)
Purchases of common stock (in shares)		(7,100,000)
Stock options exercised	19,099	$ 8	19,091
Stock options exercised (in shares)		814,000
Stock-based compensation	5,841		5,841
Excess tax benefits from stock-based compensation	3,390		3,390
Net earnings	516,361			516,361
Other comprehensive income (loss)	(38,567)				(38,567)
Balance at Dec. 31, 2015	$ 1,801,289	$ 2,896	$ 2,024	$ 1,842,772	$ (46,403)
Balance (in shares) at Dec. 31, 2015	289,581,682	289,582,000