Impaired Loans by Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Impaired [Line Items]
Average impaired loans for the period	$ 38,379	$ 57,438	$ 68,377
Contractual interest income due on impaired loans during the period	2,612	4,433	4,973
Interest income on impaired loans recognized on a cash basis	1,374	1,121	1,523
Interest income on impaired loans recognized on an accrual basis	473	560	325
Commercial
Financing Receivable, Impaired [Line Items]
Average impaired loans for the period	7,153	8,659
Contractual interest income due on impaired loans during the period	452	527
Interest income on impaired loans recognized on a cash basis	238	121
Interest income on impaired loans recognized on an accrual basis	133	257
All Other
Financing Receivable, Impaired [Line Items]
Average impaired loans for the period	6,784	6,499
Contractual interest income due on impaired loans during the period	227	112
Interest income on impaired loans recognized on a cash basis	83	82
Interest income on impaired loans recognized on an accrual basis	233	201
Commercial Real Estate Portfolio Segment | Commercial Acquisition, Development and Construction
Financing Receivable, Impaired [Line Items]
Average impaired loans for the period	5,451	12,270
Contractual interest income due on impaired loans during the period	654	1,222
Interest income on impaired loans recognized on a cash basis	253	323
Interest income on impaired loans recognized on an accrual basis	0	0
Commercial Real Estate Portfolio Segment | Commercial Investor Real Estate
Financing Receivable, Impaired [Line Items]
Average impaired loans for the period	10,605	13,838
Contractual interest income due on impaired loans during the period	587	1,181
Interest income on impaired loans recognized on a cash basis	75	175
Interest income on impaired loans recognized on an accrual basis	30	0
Commercial Real Estate Portfolio Segment | Commercial Owner Occupied Real Estate
Financing Receivable, Impaired [Line Items]
Average impaired loans for the period	8,386	16,172
Contractual interest income due on impaired loans during the period	692	1,391
Interest income on impaired loans recognized on a cash basis	725	420
Interest income on impaired loans recognized on an accrual basis	$ 77	$ 102