Consolidated Statements Of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Shareholders' Equity beginning of period at Dec. 31, 2013	$ 4,648,952	$ 3,813	$ 3,052,016	$ (795)	$ 1,593,918
Shareholders' Equity, shares beginning of period (shares) at Dec. 31, 2013		381,300
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises	5,789	$ 5	5,784
Stock option exercises (shares)		532
Stock issuances, net of cancellations		$ (1)	1
Stock issuances, net of cancellations (shares)		(68)
Dividends declared	(37,979)				(37,979)
Share repurchases	(103,711)	$ (53)			(103,658)
Share repurchases (shares)		(5,311)
Share-based compensation	8,893		8,874		19
Excess tax benefits (deficiencies) from share-based awards	(660)		(660)
Net income	116,699				116,699
Other comprehensive income	61			61
Shareholders' Equity end of period at Jun. 30, 2014	4,638,044	$ 3,764	3,066,015	(734)	1,568,999
Shareholders' Equity, shares end of period (shares) at Jun. 30, 2014		376,453
Shareholders' Equity beginning of period at Dec. 31, 2014	4,804,954	$ 3,695	3,072,996	(690)	1,728,953
Shareholders' Equity, shares beginning of period (shares) at Dec. 31, 2014		369,459
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises	7,222	$ 6	7,216
Stock option exercises (shares)		620
Stock issuances, net of cancellations	7,423	$ 4	7,419
Stock issuances, net of cancellations (shares)		442
Dividends declared	(58,227)		8		(58,235)
Share repurchases	(322,066)	$ (157)			(321,909)
Share repurchases (shares)		(15,702)
Share-based compensation	10,233		10,233
Excess tax benefits (deficiencies) from share-based awards	(1,617)		(1,617)
Net income	158,295				158,295
Other comprehensive income	42			42
Shareholders' Equity end of period at Jun. 30, 2015	$ 4,606,259	$ 3,548	$ 3,096,255	$ (648)	$ 1,507,104
Shareholders' Equity, shares end of period (shares) at Jun. 30, 2015		354,819