Summary of Activity Related to Goodwill (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Goodwill And Intangible Assets [Line Items]
Goodwill, Gross Carrying Amount Beginning Balance	$ 88,116
Increase in goodwill, Gross Carrying Amount	1,177
Goodwill, Gross Carrying Amount Ending Balance	89,293
Goodwill, Accumulated Impairment Losses Beginning Balance	(304)
Goodwill accumulated impairment losses adjustment
Goodwill, Accumulated Impairment Losses Ending Balance	(304)
Goodwill, Net Carrying Amount Beginning Balance	87,812
Increase in goodwill, Net Carrying Amount	1,177
Goodwill, Net Carrying Amount Ending Balance	$ 88,989