Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment, Depreciation Methods	straight-line method	straight-line method
Cash Reserve Deposit Required and Made	$ 15,241	$ 1,119
Minimum [Member]
Finite-Lived Intangible Asset, Useful Life	6 years	6 years
Maximum [Member]
Finite-Lived Intangible Asset, Useful Life	10 years	10 years
Building [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	10 years	10 years
Building [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	40 years	40 years
Furniture and Fixtures [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years	3 years
Furniture and Fixtures [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	10 years	10 years