Weighted Average Shares - Calculation of Weighted Average Shares (Detail) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Earnings Per Share [Abstract]
Basic weighted-average common shares outstanding	86,858	86,946	[1]	85,666	[1]
Effect of dilutive stock options	2,213	1,955		1,614
Diluted weighted-average common and common-equivalent shares outstanding	89,071	88,901	[1]	87,280	[1]

[1] Prior period results have been adjusted to reflect the two-for-one stock split effected in the form of a stock dividend which occurred in the third quarter of 2013.