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 (shares)		554
Stock option exercises	6,034	$ 5	6,029
Stock issuances, net of cancellations (shares)		(42)
Stock issuances, net of cancellations	0
Dividends declared	(56,689)		72		(56,761)
Share repurchases	(155,140)	$ (80)			(155,060)
Share repurchases (shares)		(8,034)
Share-based compensation	10,586		10,586		0
Excess tax benefits (deficiencies) from share-based awards	(660)		(660)
Net income	257,244				257,244
Other comprehensive income	82			82
Shareholders' Equity end of period at Sep. 30, 2014	4,710,409	$ 3,738	3,068,043	(713)	1,639,341
Shareholders' Equity, shares end of period (shares) at Sep. 30, 2014		373,778
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 (shares)		888
Stock option exercises	10,371	$ 9	10,362
Stock issuances, net of cancellations (shares)		431
Stock issuances, net of cancellations	7,423	$ 4	7,419
Dividends declared	(86,296)		8		(86,304)
Share repurchases	(442,738)	$ (216)			(442,522)
Share repurchases (shares)		(21,641)
Share-based compensation	13,556		13,556
Excess tax benefits (deficiencies) from share-based awards	(1,790)		(1,790)
Net income	266,062				266,062
Other comprehensive income	63			63
Shareholders' Equity end of period at Sep. 30, 2015	$ 4,571,605	$ 3,492	$ 3,102,551	$ (627)	$ 1,466,189
Shareholders' Equity, shares end of period (shares) at Sep. 30, 2015		349,137