Goodwill and Other Acquired Intangible Assets - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2012
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Goodwill impairment charge	$ 12.2		$ 12.2
Intangible assets impairment charge		$ 1