Summary of Estimated Future Expense Stemming from Amortization of Core Deposit Intangibles (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Expected Amortization Expense [Line Items]
Total remaining intangible assets	$ 15,784	$ 19,644	$ 26,066
Core deposit intangibles
Expected Amortization Expense [Line Items]
2014	8,297
2015	5,345
2016	2,391
2017	207
Total remaining intangible assets	$ 16,240