Pension Plan (Detail) (USD $)	Jun. 30, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Pension Plan Liabilities, Current	$ 800,000
Defined Benefit Pension Plan, Liabilities, Noncurrent	5,000,000
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Minimum Pension Liability, before Tax	900,000
Deferred Tax Liabilities, Deferred Expense		$ 559,000	$ 285,000