Pension and Other Post-Retirement Benefits - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended
Apr. 30, 2013 Funded Pension Plans [Member]	Mar. 31, 2013 Unfunded Pension Plans [Member]	Mar. 31, 2013 Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit payment amount	$ 16.8	$ 0.9	$ 0.2
Estimated additional payments in 2012		$ 2.7	$ 0.6

The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. This item represents a periodic decrease to the plan obligations and a decrease to plan assets.

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+ Details