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)		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected dividend yield	[1]	0.00%	0.00%
Expected stock price volatility	[2]	24.00%	25.00%
Risk-free interest rate	[3]	1.50%	1.30%
Expected life in years	[4]	4 years 4 months 24 days	4 years 4 months 24 days

[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).