Non-Covered Loans and Allowance for Non-Covered Loan Losses (Details 3) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2012
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Days outstanding loans and leases receivable are generally considered past due		90 days
Non-covered loans
Non-covered PCI loans
Unpaid Contractual Principal balance	$ 187,370,000	$ 187,370,000	$ 222,674,000
Nonaccretable Difference	47,365,000	47,365,000	61,378,000
Accretable Yield	21,443,000	21,443,000	17,553,000
Total Recorded Investment	139,224,000	139,224,000	166,780,000
Related Allowance	3,011,000	3,011,000
Average investment in PCI loans
Average investment in PCI loans	138,768,000	153,003,000
Non-accrual loans	19,212,000	19,212,000
Non-covered loans | Bank
Average investment in PCI loans
Unadvanced commitments to borrowers	300,000	300,000
Non-covered loans | Secured
Non-covered PCI loans
Unpaid Contractual Principal balance	71,924,000	71,924,000	91,633,000
Nonaccretable Difference	16,557,000	16,557,000	24,982,000
Accretable Yield	4,401,000	4,401,000	6,114,000
Total Recorded Investment	56,831,000	56,831,000	67,967,000
Related Allowance	2,732,000	2,732,000
Average investment in PCI loans
Average investment in PCI loans	55,797,000	62,399,000
Non-accrual loans	16,009,000	16,009,000
Non-covered loans | Unsecured
Non-covered PCI loans
Unpaid Contractual Principal balance	9,678,000	9,678,000	12,198,000
Nonaccretable Difference	5,062,000	5,062,000	8,707,000
Accretable Yield	3,937,000	3,937,000	472,000
Total Recorded Investment	1,676,000	1,676,000	3,419,000
Average investment in PCI loans
Average investment in PCI loans	1,826,000	2,548,000
Non-accrual loans	23,000	23,000
Non-covered loans | Secured by commercial properties
Non-covered PCI loans
Unpaid Contractual Principal balance	51,525,000	51,525,000	66,736,000
Nonaccretable Difference	11,704,000	11,704,000	15,816,000
Accretable Yield	7,236,000	7,236,000	7,294,000
Total Recorded Investment	42,077,000	42,077,000	55,519,000
Related Allowance	205,000	205,000
Average investment in PCI loans
Average investment in PCI loans	45,114,000	48,798,000
Non-accrual loans	1,856,000	1,856,000
Non-covered loans | Secured by residential properties
Non-covered PCI loans
Unpaid Contractual Principal balance	6,141,000	6,141,000	8,690,000
Nonaccretable Difference	1,140,000	1,140,000	2,251,000
Accretable Yield	904,000	904,000	557,000
Total Recorded Investment	4,636,000	4,636,000	6,728,000
Related Allowance	73,000	73,000
Average investment in PCI loans
Average investment in PCI loans	5,400,000	5,682,000
Non-accrual loans	161,000	161,000
Non-accrual loans held for sale	2,700,000	2,700,000	1,800,000
Non-covered loans | Residential construction loan
Non-covered PCI loans
Unpaid Contractual Principal balance			995,000
Nonaccretable Difference			493,000
Accretable Yield			40,000
Total Recorded Investment			708,000
Average investment in PCI loans
Average investment in PCI loans		354,000
Non-covered loans | Commercial construction loans and land development
Non-covered PCI loans
Unpaid Contractual Principal balance	35,012,000	35,012,000	42,330,000
Nonaccretable Difference	9,637,000	9,637,000	9,113,000
Accretable Yield	3,940,000	3,940,000	3,067,000
Total Recorded Investment	24,641,000	24,641,000	32,362,000
Related Allowance	1,000	1,000
Average investment in PCI loans
Average investment in PCI loans	25,916,000	28,502,000
Non-accrual loans	1,073,000	1,073,000
Non-covered loans | Consumer
Non-covered PCI loans
Unpaid Contractual Principal balance	13,090,000	13,090,000	92,000
Nonaccretable Difference	3,265,000	3,265,000	16,000
Accretable Yield	1,025,000	1,025,000	9,000
Total Recorded Investment	9,363,000	9,363,000	77,000
Average investment in PCI loans
Average investment in PCI loans	4,715,000	4,720,000
Non-covered loans | PCI
Non-covered PCI loans
Total Recorded Investment	1,100,000	1,100,000
Average investment in PCI loans
Non-accrual loans	$ 18,100,000	$ 18,100,000