Fair Value Measurements (Details 4) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Deposits
Carrying amount of time deposits	$ 2,702,052,000	$ 2,954,312,000
Significant Unobservable Inputs (Level 3)
Assets and liabilities reported at fair value on recurring
Estimated fair value of fixed rate performing loans	1,152,663,000	1,126,228,000
Loans
Carrying amount of fixed rate performing loans	1,207,154,000	1,189,585,000
Deposits
Carrying amount of time deposits	2,702,052,000	2,954,312,000
Estimated fair value of time deposits	2,695,908,000	2,962,190,000
Securities Sold Under Repurchase Agreements
Carrying amount of long-term repurchase agreements	710,000,000	800,000,000
Estimated fair value of long-term repurchase agreements	799,005,000	932,007,000
Significant Other Observable Inputs (Level 2)
Other borrowed funds
Carrying amount of the long-term FHLB borrowings	8,993,000	6,527,000
Estimated fair value of long-term FHLB borrowings	$ 8,993,000	$ 7,073,000