Fair Value of Financial Instruments - Disclosures About Fair Value of Assets and Liabilities - Additional Information (Detail) (Significant Unobservable Inputs (Level 3), USD $)	12 Months Ended
	Dec. 31, 2012
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trust preferred securities, carrying value	$ 6,100,000
Trust preferred securities, fair value	194,000
Other-than-temporary impairment ("OTTI") loss	$ 104,000