Share Based Compensation - Additional Information (Detail) (USD $)	12 Months Ended					12 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 2011 Incentive Plan	Dec. 31, 2012 2011 Incentive Plan	Dec. 31, 2001 2001 Stock Option Plan Y	Dec. 31, 2012 2001 Stock Option Plan	Dec. 31, 2001 2001 Stock Option Plan Incentive Stock Options	Dec. 31, 2001 2001 Stock Option Plan Non-Qualified Stock Options	Dec. 31, 2012 Two Thousand Four Stock Incentive Plan	Dec. 31, 2011 Two Thousand Four Stock Incentive Plan	Dec. 31, 2010 Two Thousand Four Stock Incentive Plan	Dec. 31, 2012 Stock Options Y	Dec. 31, 2011 Stock Options	Dec. 31, 2010 Stock Options	Dec. 31, 2012 Stock Options Minimum	Dec. 31, 2012 Stock Options Maximum	Dec. 31, 2012 Stock Options Awards That Contain Performance Or Market Conditions Y	Dec. 31, 2011 Stock Options Awards That Contain Performance Or Market Conditions	Dec. 31, 2010 Stock Options Awards That Contain Performance Or Market Conditions	Dec. 31, 2012 Restricted Stock	Dec. 31, 2011 Restricted Stock	Dec. 31, 2010 Restricted Stock	Dec. 31, 2012 Restricted Stock Director	Dec. 31, 2012 Restricted Stock Minimum	Dec. 31, 2012 Restricted Stock Maximum	Dec. 31, 2012 1998 ESPP	Dec. 31, 2011 1998 ESPP	Dec. 31, 2010 1998 ESPP	Dec. 31, 2012 1998 ESPP Minimum	Dec. 31, 2012 Restricted Stock Units (RSUs) Minimum Director	Dec. 31, 2012 Restricted Stock Units (RSUs) Maximum Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Purchase Plan, purchase discount								100.00%	85.00%																					5.00%
Shares authorized to purchase upon grant of options							10,000,000
Unexercised options expiration period or after termination of employment, years						10
Common stock issued upon exercise of outstanding stock options		33,000	273,000	7,750,000
Shares remain available for future grant					2,461,620
Stock compensation expense	$ 6,932,000	$ 7,900,000	$ 7,784,000							$ 6,900,000	$ 7,900,000	$ 7,800,000															$ 900,000	$ 800,000	$ 300,000
Exercise of stock options and the vesting of restricted stock, income tax deduction	600,000
Vesting period	2 years												4 years			1 year	4 years							1 year	1 year	4 years					31 days	1 year
Term of options granted from grant date, years													10					10
Proceeds from exercise of outstanding stock options		200,000	1,800,000
Stock option compensation cost charged against operations													4,000,000	3,200,000	2,300,000			21,000	600,000	800,000	2,600,000	2,600,000	2,100,000
Unrecognized compensation cost	3,200,000																				3,400,000
Unamortized stock option compensation, expected to be recognized over a weighted-average period, years	1 year 10 months 24 days
Total intrinsic value of options exercised														100,000	2,300,000
Closing price of common stock													$ 1.05	$ 2.23	$ 11.14
Income as result of reversal of prior compensation expense	500,000
Options remain unvested	953,000																				1,830,000
Additional compensation expense if the performance targets are met or expected to be attained	900,000
Shares of restricted stock issued																					1,854,000	856,000	43,000
Weighted-average grant date fair value for restricted stock awards granted																					$ 1.83	$ 8.35	$ 11.72
Total aggregate fair market value of restricted stock issued																					3,400,000	7,100,000	500,000
Total fair value of restricted stock and restricted stock units vested																					500,000	1,600,000	2,800,000
Employee Stock Purchase Plan, purchase price																														85.00%
Employee options to purchase shares of common stock													1,806,000														491,195	155,097	29,738
Additional paid-in-capital excess tax benefit pool available to absorb future tax deficiencies	$ 1,900,000