Goodwill and Other Acquired Intangible Assets - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule Of Goodwill And Other Intangible Assets [Line Items]
Goodwill impairment charge		$ 1,000,000	$ 1,000,000			$ 12,200,000
Intangible assets impairment charge	$ 1,000,000