Annual report pursuant to Section 13 and 15(d)

Variations from Federal Statutory Rate (Parenthetical) (Detail)

v2.4.0.6
Variations from Federal Statutory Rate (Parenthetical) (Detail)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Reconciliation Of Income Taxes [Line Items]      
Expected federal income tax expense (benefit), statutory rate 34.00% 34.00% 34.00%