Loans and Allowance for Loan Losses (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Changes in the carrying amount of accretable difference for acquired impaired and non-impaired loans
Threshold limit for provision of specific reserve on impaired loan	$ 250,000
Acquired loans | Credit impaired
Changes in the carrying value of acquired loans at the acquisition date
Balance at the beginning of the period	969,395,000	370,581,000
Fair value of acquired loans	591,951,000	766,087,000
Net reductions for payments, foreclosures, and accretion	(344,348,000)	(166,761,000)
Change in the allowance for loan losses on acquired loans	(918,000)	(512,000)
Balance at the end of the period	1,216,080,000	969,395,000
Changes in the carrying amount of accretable difference for acquired impaired and non-impaired loans
Balance at beginning of period	160,849,000	94,600,000
Interest income	(104,705,000)	(52,628,000)
Reclass of nonaccretable difference due to improvement in expected cash flows	71,136,000	35,739,000
Other changes, net	(7,720,000)	(11,864,000)
Balance at end of period	250,340,000	160,849,000
Threshold limit for provision of specific reserve on impaired loan	250,000
Threshold limit of loans for risk assessment by loan officers	25,000
Previous threshold limit of loans for risk assessment by loan officers	500,000
Acquired loans | Credit impaired | First Financial
Changes in the carrying amount of accretable difference for acquired impaired and non-impaired loans
Addition from acquisition	130,780,000
Acquired loans | Credit impaired | Peoples
Changes in the carrying amount of accretable difference for acquired impaired and non-impaired loans
Addition from acquisition		34,921,000
Acquired loans | Credit impaired | Savannah
Changes in the carrying amount of accretable difference for acquired impaired and non-impaired loans
Addition from acquisition		$ 60,081,000