Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Additional Information (Detail)

v2.4.0.6
Fair Value Measurements - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
Jun. 30, 2012
Dec. 31, 2011
Fair Value, Measurement Inputs, Disclosure [Line Items]    
Long-term debt, carrying value $ 1,833.3 $ 1,834.5
Long-term debt, fair value $ 2,110.6 $ 2,079.5