Weighted Average Assumptions used in Black Scholes Option Valuation Model (Detail)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Share Based Payment Award Stock Options Valuation Assumptions [Line Items]
Expected volatility	54.00%	[1]	45.00%	[1]	41.00%	[1]
Expected term in years	4 years 3 months 18 days	[2]	5 years 1 month 6 days	[2]	5 years 1 month 6 days	[2]
Risk-free interest rate	0.63%	[3]	1.18%	[3]	1.65%	[3]
Expected annual dividend yield	0.52%	[4]	0.58%	[4]	0.71%	[4]

[1] The expected volatility for each grant is determined based on the average of historical weekly price changes of the Company's common stock over a period of time which approximates the expected option term.

[2] The expected option term for each grant is determined based on the historical exercise behavior of employees and post-vesting employment termination behavior.

[3] The risk-free interest rate is based on the yield of zero-coupon U.S. Treasury securities for a period that is commensurate with the expected option term at the time of grant.

[4] The expected annual dividend yield is based on the weighted-average of the dividend yield assumptions used for options granted during the applicable period. The expected annual dividend is based on the expected dividend of $0.12 per share, per year ($0.03 per share, per quarter times 4 quarters) divided by the average stock price.