Share Based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended			6 Months Ended			3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 1999 Stock Option Plan OptionPlan	Jun. 30, 2012 2005 Omnibus Stock Plan OptionPlan	Jun. 30, 2012 2005 Omnibus Stock Plan Maximum	Jun. 30, 2012 2005 Omnibus Stock Plan Minimum	Jun. 30, 2012 Stock Options And Restricted Stock Units	Jun. 30, 2011 Stock Options And Restricted Stock Units	Jun. 30, 2012 Stock Options And Restricted Stock Units	Jun. 30, 2011 Stock Options And Restricted Stock Units	Mar. 31, 2012 Stock Option	Jun. 30, 2012 Stock Option	Mar. 31, 2012 Restricted Stock	Jun. 30, 2012 Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share based compensation plan					1	1
Common stock, shares authorizes							1,800,000
Common stock, shares available for issuance							958,292
Exercise period, maximum			5 years 4 months 6 days	5 years 8 months 12 days		10 years	10 years	7 years
Minimum grant price percentage						100.00%
Recognized Compensation expense									$ 0.3	$ 0.3	$ 0.6	$ 0.6
Unrecognized Compensation expense	3.6		3.6											0.4
Expected cost recognition weighted average period														1 year 10 months 24 days		3 years 4 months 24 days
Fair value of shares vested	$ 0.2	$ 0.3
Stock granted			20,633,000										20,633		83,807
Vesting period													3 years		5 years