Premises and Equipment - Summary of Premises and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 67,412	$ 79,033
Accumulated depreciation	32,338	43,855
Property, plant and equipment, net	35,074	35,178
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	2,052	1,362
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,791	4,030
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	35,925	35,506
Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 24,644	$ 38,135