Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended		1 Months Ended		1 Months Ended	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Oct. 25, 2011 Court Proceeding	Dec. 02, 2011 Court Proceeding	Dec. 02, 2011 Pending or Threatened Litigation	Mar. 31, 2012 Settlement Agreement
Loss Contingencies [Line Items]
Statutory interest rate			9.00%
Partial Summary Judgment Order				$ 4,700,000
Interest expense accrual	5,412,000	858,000			4,700,000	4,500,000
Settlement amount						$ 9,200,000
Settlement agreement, effective date						Apr. 19, 2012