Other Noninterest Income - Components of Other Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Other Noninterest Income [Line Items]
Income from bank owned life insurance	$ 2,774	$ 3,108	$ 8,452	$ 6,271
Safety deposit box income	502	541	1,524	1,077
Credit related fees	1,545	2,261	5,130	3,573
Income from derivatives	455	101	2,091	95
Gain on sale of assets	1,991	(64)	2,195	544
Other miscellaneous	2,503	2,219	6,709	4,611
Total other noninterest income	$ 9,770	$ 8,166	$ 26,101	$ 16,171