Shareholders' Equity - Summary of Changes in Shareholders' Equity (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended				9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Common Stock [Member]	Dec. 31, 2013 Common Stock [Member]	Sep. 30, 2014 Additional Paid-In-Capital [Member]	Sep. 30, 2014 Retained Earnings [Member]	Sep. 30, 2014 Treasury Stock [Member]	Sep. 30, 2014 Deferred Compensation Trust [Member]	Sep. 30, 2014 Deferred Compensation Liability [Member]
Stockholders' Equity [Line Items]
Beginning Balance			$ 1,261,352		$ 206	$ 206	$ 1,212,050	$ 4,605,557	$ (4,556,461)	$ (17,741)	$ 17,741
Net income	90,152	82,935	182,179	168,666				182,179
Deferred compensation activity			0							408	(408)
Purchase of common stock for treasury			(409,436)						(409,436)
Equity-based compensation			44,874				44,874
Tax benefit from equity benefit plan activity			6,786				6,786
Proceeds from stock options exercised			65,639	7,564			65,639
Treasury stock issued upon option exercise and restricted share vesting			0				(29,816)		29,816
Ending Balance	$ 1,151,394		$ 1,151,394		$ 206	$ 206	$ 1,299,533	$ 4,787,736	$ (4,936,081)	$ (17,333)	$ 17,333