Summary of Stock Option Transactions Relating to Non-Qualified Stock Option Plans (Detail) (Nonvested Stock Option, USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Number of Shares
No. of options, Outstanding at December 31, 2012	4,047
No. of options, Granted
Special dividend adjustment	519
No. of options, Exercised	(1,830)
No. of options, Cancelled	(134)
No. of options, Outstanding at December 31, 2013	2,602
No. of options, Exercisable at December 31, 2013	1,923
Weighted-Average Exercise Price per Share
Weighted-Average Exercise Price of options, Outstanding at December 31, 2012	$ 20.61
Weighted-Average Exercise Price of options, Granted
Weighted-Average Exercise Price of options, Exercised	$ 16.48
Weighted-Average Exercise Price of options, Cancelled	$ 22.33
Weighted-Average Exercise Price of options, Outstanding at December 31, 2013	$ 19.31
Weighted-Average Exercise Price of options, Exercisable at December 31, 2013	$ 18.47
Weighted Average Remaining Contractual Term (in years)
Outstanding at December 31, 2013	5 years 9 months 18 days
Exercisable at December 31, 2013	5 years 1 month 6 days
Aggregate Intrinsic Value
Outstanding at December 31, 2013	$ 33,197
Exercisable at December 31, 2013	$ 26,141
Special Dividend
Weighted-Average Exercise Price per Share
Weighted-Average Exercise Price of options, Special dividend adjustment