Mortgage Banking Activities - Capitalized Mortgage Servicing Rights (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2012
Mortgage Banking [Abstract]
Beginning balance			$ 5,941,000	$ 5,506,000
Originations			958,000	2,228,000
Amortized to expense	(435,000)	(482,000)	(1,259,000)	(1,712,000)
Ending balance	5,640,000	6,022,000	5,640,000	6,022,000
Less valuation allowance	(4,000)	(4,000)	(4,000)	(4,000)	(680,000)	(680,000)
Net balance	$ 5,636,000	$ 6,018,000	$ 5,636,000	$ 6,018,000