Credit Quality Assessment (Summary of Impaired Loans) (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Credit Quality Assessment [Abstract]
Impaired loans with a specific allowance	$ 9,661	$ 11,411
Impaired loans without a specific allowance	19,033	18,008
Total impaired loans	28,694	29,419
Allowance for loan and lease losses related to impaired loans	2,886	2,894
Allowance for loan and lease losses related to loans collectively evaluated	35,827	34,908
Total allowance for loan and lease losses	38,713	37,802
Average impaired loans for the period	28,769	34,331
Contractual interest income due on impaired loans during the period	1,326	2,339
Interest income on impaired loans recognized on a cash basis	324	773
Interest income on impaired loans recognized on an accrual basis	$ 122	$ 280