Stock-Based Compensation (Detail) - Weighted-Average Assumptions Used To Determine Fair Value Of SARs Grants On Date Of Grant Using Black-Scholes-Merton Valuation Model (Stock appreciation rights (SARs))	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Stock appreciation rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected dividend yield	0.00%	[1]	0.00%	[1]
Expected stock price volatility	24.00%	[2]	25.00%	[2]
Risk-free interest rate	1.50%	[3]	1.30%	[3]
Expected life in years	4 years 4 months 24 days	[4]	4 years 4 months 24 days	[4]

[1] The dividend yield assumption is based on the history and expectation of the Company’s dividend payouts. Historically the Company has not paid cash dividends on its Common Stock.

[2] The determination of expected stock price volatility was based on both historical Common Stock prices and implied volatility from publicly traded options in the Common Stock.

[3] The risk-free interest rate is based on the yield of a U.S. Treasury security with a maturity similar to the expected life of the award.

[4] The expected life represents the Company’s weighted-average estimate of the period of time the SARs are expected to be outstanding (that is, period between the service inception date and the expected exercise date).