Stock-based Compensation (Summary of Stock Option Plan Activity) (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Stock-based Compensation [Abstract]
Outstanding, beginning of period, Shares	2,049,173	2,892,882
Granted, Shares	683,200	537,300
Exercised, Shares	(243,491)	(798,790)
Forfeited or cancelled, Shares	(34,085)	(164,500)
Outstanding, end of period, Shares	2,454,797	2,466,892
Outstanding, beginning of period, Weighted Average Exercise Price	$ 41.18	$ 38.28
Granted, Weighted Average Exercise Price	$ 58.02	$ 42.51
Exercised, Weighted Average Exercise Price	$ 38.66	$ 32.84
Forfeited or cancelled, Weighted Average Exercise Price	$ 41.84	$ 41.74
Outstanding, end of period, Weighted Average Exercise Price	$ 46.10	$ 40.74