Share-Based compensation - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended	6 Months Ended		1 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Jun. 30, 2012 Maximum Year	Jun. 30, 2012 Minimum Year	Sep. 10, 2004 Stock Incentive Plan 2004	Sep. 10, 2004 Stock Incentive Plan 2004 Maximum	Aug. 27, 2008 Stock Option Plan 2008	Aug. 27, 2008 Stock Option Plan 2008 Maximum	Sep. 10, 2004 Employee Stock Option Plan, 2004	Aug. 19, 1999 Stock Option Plan 1997	Oct. 31, 1994 Stock Option Plan 1994
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share Based Compensation Expense		$ 4,000		$ 9,000
Issuance of Stock Option to Purchase Stock	5,500,000		5,500,000
Common stock reserved for issuance	2,667,000		2,667,000							3,000,000		2,500,000	2,000,000	725,000
Stock option awards vesting period						2 years
Stock option awards contractual term						10	5
Options Granted					75,000
Unrecognized Compensation Cost Related to Non-Vested
Plan Expiration Date										Aug. 27, 2018		Sep. 10, 2014	Jun. 11, 2007	Nov. 01, 2004
Options Grant, expiration period, Years, Maximum								5 years	10 years	5 years	10 years
Intrinsic Value of Options Exercised					$ 700