Stockholders' Equity - Additional Information (Detail) (USD $)	12 Months Ended			12 Months Ended		12 Months Ended		12 Months Ended			12 Months Ended			1 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012 2008 Plan [Member]	Dec. 31, 2012 2008 Plan [Member]	Dec. 31, 2010 Other [Member]	Dec. 31, 2012 Other [Member]	Dec. 31, 2012 Qualified Stock Option Plans [Member]	Dec. 31, 2011 Qualified Stock Option Plans [Member]	Dec. 31, 2011 Qualified Stock Option Plans [Member] 2008 Plan [Member]	Dec. 31, 2012 Non-Qualified Stock Option Plans [Member]	Dec. 31, 2011 Non-Qualified Stock Option Plans [Member]	Dec. 31, 2011 Non-Qualified Stock Option Plans [Member] 2008 Plan [Member]	Dec. 31, 2012 Non-Qualified Stock Option Plans [Member] 2008 Plan [Member]	Dec. 31, 2012 Non-Qualified Stock Option Plans [Member] Outside Director Plan [Member]	Jun. 14, 2007 Non-Qualified Stock Option Plans [Member] 2006 Options [Member]	Dec. 31, 2012 Preferred Share Rights Plan [Member]
Stockholders Equity [Line Items]
Date of approval of stock incentive plan	Jun. 05, 2008
Number of common stock shares for issuance			1,000,000										400,000
Minimum exercise price of stock option at grant date		No less than 100% of the fair market value, as defined in the 2008 Plan, of the shares on the date of grant
Percentage of fair market value		100.00%
Maximum term of stock option		10 years
Number of shares of stock options granted								249,000			5,000			450,000
Qualified and Non-Qualified Options vest at a percentage rate for first 5 years		16.50%
Qualified and Non-Qualified Options final year vesting		End of the sixth year
Exercisable period Non-Qualified Options following termination event		Fully vested and exercisable for a period of one year from the date of the termination event
Exercisable period after termination		1 year
Term of historical volatility of common stock	6 years
Total stock-based compensation expense not yet recognized, relating to non-vested stock options		$ 6,265,000
Exercise price of Options						$ 15.73			$ 8.32					$ 8.01
Stock options available for grant			349,905										280,000
Stock option plans, options outstanding			467,915			478,915	516,330		258,050	316,525		38,050
Stock options plan, options Exercisable												20,275
Preferred share right plan description															If a person or group acquires 15% or more of our common stock, each Right will entitle the holder (other than the person or group that triggered the Rights being exercisable) to purchase shares of our common stock (or, in certain circumstances, cash or other securities) having a market value of twice the exercise price of a Right at such time
Minimum percentage of ownership of common stock required to exercise preferred share rights															15.00%
Exercise price of Preferred Stock															47.75 per one one-hundredth of a share
Redemption price preferred share rights															$ 0.01
Maximum time for redemption after the Rights become exercisable															10 days
Preferred share right exchange ratio															One common share per Right
Minimum percentage of beneficial ownership of common stock to end preferred share rights exchange															Until the person triggering the Right becomes the beneficial owner of 50% or more of our common stock.
Number of shares of treasury stock purchased				177,100
Average price of treasury stock				$ 13.67
Number of shares converted					1,700,000