Disclosures about Fair Value of Assets and Liabilities - Realized Gains and Losses included in Net Income for Periods in Condensed Consolidated Statements of Income (Detail) (Non Interest Income Total gains and losses [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Included in net income	$ 210	$ (396)	$ 450	$ (408)
Hedged Loans [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Included in net income	544	(1,444)	751	(1,846)
Fair value interest rate swap agreements [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Included in net income	(544)	1,444	(751)	1,846
Derivative loan commitments [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Included in net income	$ 210	$ (396)	$ 450	$ (408)