Goodwill - Additional Information (Detail) (USD $)	9 Months Ended
Sep. 30, 2012 Segment	Sep. 30, 2011
Goodwill [Line Items]
Goodwill Impairment Charges	$ 0	$ 0
Number of reportable segments	4

Loss recognized during the period that results from the write-down of goodwill after comparing the implied fair value of reporting unit goodwill with the carrying amount of that goodwill. Goodwill is assessed at least annually for impairment.

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+ Details