Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013 Office Contract	Sep. 30, 2012	Sep. 30, 2013 Branches Contract Segment Office	Sep. 30, 2012
Operations And Summary Of Significant Accounting Policies [Line Items]
Real estate development and construction maximum family residential units			4
Real estate development and construction minimum family residential units			1
Number of real estate joint ventures currently involved			8
Number of full service banking branches			23
Number of loan production offices	1		1
Number of operating segment			1
Stock-based compensation expense	$ 186,000	$ 116,000	$ 537,000	$ 327,000
Tax benefit from compensation expense	12,000	6,000	49,000	23,000
Unrecognized compensation cost	727,000		727,000
Share based compensation expense recognized, years			4 years
Interest rate cap contracts outstanding	21		21
Interest payment in junior subordinated notes	35,000,000		35,000,000
Number of interest rate swap contracts			2
Minimum cumulative percentage change in anticipated cash flows			80.00%
Maximum cumulative percentage change in anticipated cash flows			125.00%
Amounts charged to current earnings	0		0
Interest Rate Swaps [Member]
Operations And Summary Of Significant Accounting Policies [Line Items]
Interest payment in junior subordinated notes	35,000,000		35,000,000
Interest Rate Caps [Member]
Operations And Summary Of Significant Accounting Policies [Line Items]
Interest payment in junior subordinated notes	$ 220,000,000		$ 220,000,000
AMSCO Inc [Member]
Operations And Summary Of Significant Accounting Policies [Line Items]
Ownership percentage			51.00%