v2.4.0.6
Significant Accounting Policies - Additional Information (Detail)
12 Months Ended
Dec. 31, 2012
Significant Accounting Policies [Line Items]  
Attributable to hedged risk, range minimum 80.00%
Attributable to hedged risk, range maximum 125.00%
Percentage of income tax benefit recognized 50.00%
Percentage of fair value of plan assets 10.00%