Assets Acquired In FDIC-Assisted Acquisitions (Narrative) (Detail) (USD $)	6 Months Ended
	Jun. 30, 2012	Feb. 24, 2012 Facility	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
FDIC Shared-loss agreements	80.00%
FDIC Shared-loss agreements loss recoveries	80.00%
Number of branches		5
Estimated FDIC indemnification asset	$ 203,801,000		$ 242,394,000	$ 160,927,000	$ 177,187,000
Before-tax gain on acquisition	23,037,000
Total loans acquired	137,200,000
Total loans acquired, fair value	73,400,000
Accretable yield	10,200,000
Central Bank of Georgia (CBG)
Bid to acquire assets	33,900,000
Cash payment from FDIC to settle acquisition	31,900,000
Estimated FDIC indemnification asset	52,700,000
Before-tax gain on acquisition	20,000,000
Deferred tax liabilities recorded with respect to acquisitions	7,000,000
After-tax gain on acquisition	$ 13,000,000