Shareholders' Equity - Summary of Changes in Shareholders' Equity (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Common Stock [Member]	Dec. 31, 2013 Common Stock [Member]	Mar. 31, 2014 Additional Paid-In-Capital [Member]	Mar. 31, 2014 Retained Earnings [Member]	Mar. 31, 2014 Treasury Stock [Member]	Mar. 31, 2014 Deferred Compensation Trust [Member]	Dec. 31, 2013 Deferred Compensation Trust [Member]	Mar. 31, 2014 Deferred Compensation Liability [Member]	Dec. 31, 2013 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)	$ 17,741	$ 17,741
Net income	23,849	35,041				23,849
Purchase of common stock for treasury	(32,578)						(32,578)
Equity-based compensation	10,703				10,703
Tax benefit from equity benefit plan activity	5,696				5,696
Proceeds from stock options exercised	57,060	5,412			57,060
Treasury stock issued upon option exercise and restricted share vesting					(26,099)		26,099
Ending Balance	$ 1,326,082		$ 206	$ 206	$ 1,259,410	$ 4,629,406	$ (4,562,940)	$ (17,741)	$ (17,741)	$ 17,741	$ 17,741