Net Interest Income and Noninterest Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Segment Reporting Information [Line Items]
Net interest income	$ 8,144	$ 8,592	$ 16,159	$ 17,198
Noninterest income	9,126	1,858	15,154	3,216
Asset	1,076,123		1,076,123		1,024,552
Commercial Banking
Segment Reporting Information [Line Items]
Net interest income	7,228	8,360	14,696	16,842
Noninterest income	676	529	2,173	995
Asset	875,834		875,834		933,436
Mortgage Segment
Segment Reporting Information [Line Items]
Net interest income	1,033	344	1,689	576
Noninterest income	8,450	1,329	12,981	2,221
Asset	186,143		186,143		86,614
All Other Segments
Segment Reporting Information [Line Items]
Net interest income	(117)	(112)	(226)	(220)
Asset	$ 14,146		$ 14,146		$ 4,502