Loans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Analysis of allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period	$ 44,275	$ 58,884
Additions (deductions) [Abstract]
Provision for loan losses	(691)	5,131
Recoveries credited to allowance	1,451	1,880
Loans charged against the allowance	(4,270)	(9,889)
Balance at end of period	40,765	56,006
Allowance for loan losses [Abstract]
Individually evaluated for impairment	19,800		21,009
Collectively evaluated for impairment	20,965		23,266
Total ending allowance balance	40,765		44,275
Loans [Abstract]
Individually evaluated for impairment	149,147		151,167
Collectively evaluated for impairment	1,246,585		1,272,801
Total loans recorded investment	1,395,732		1,423,968
Accrued interest included in recorded investment	4,870		4,829
Total Loans	1,390,862		1,419,139
Commercial [Member]
Analysis of allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period	11,402	18,183
Additions (deductions) [Abstract]
Provision for loan losses	(272)	1,496
Recoveries credited to allowance	536	1,006
Loans charged against the allowance	(1,608)	(4,244)
Balance at end of period	10,058	16,441
Allowance for loan losses [Abstract]
Individually evaluated for impairment	5,936		6,558
Collectively evaluated for impairment	4,122		4,844
Total ending allowance balance	10,058		11,402
Loans [Abstract]
Individually evaluated for impairment	56,309		55,634
Collectively evaluated for impairment	557,711		563,316
Total loans recorded investment	614,020		618,950
Accrued interest included in recorded investment	1,689		1,692
Total Loans	612,331		617,258
Mortgage [Member]
Analysis of allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period	21,447	22,885
Additions (deductions) [Abstract]
Provision for loan losses	(139)	4,235
Recoveries credited to allowance	622	548
Loans charged against the allowance	(1,767)	(4,397)
Balance at end of period	20,163	23,271
Allowance for loan losses [Abstract]
Individually evaluated for impairment	12,370		12,869
Collectively evaluated for impairment	7,793		8,578
Total ending allowance balance	20,163		21,447
Loans [Abstract]
Individually evaluated for impairment	85,489		88,028
Collectively evaluated for impairment	432,744		441,703
Total loans recorded investment	518,233		529,731
Accrued interest included in recorded investment	2,437		2,391
Total Loans	515,796		527,340
Installment [Member]
Analysis of allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period	3,378	6,146
Additions (deductions) [Abstract]
Provision for loan losses	375	289
Recoveries credited to allowance	286	326
Loans charged against the allowance	(877)	(1,227)
Balance at end of period	3,162	5,534
Allowance for loan losses [Abstract]
Individually evaluated for impairment	1,494		1,582
Collectively evaluated for impairment	1,668		1,796
Total ending allowance balance	3,162		3,378
Loans [Abstract]
Individually evaluated for impairment	7,349		7,505
Collectively evaluated for impairment	177,819		183,090
Total loans recorded investment	185,168		190,595
Accrued interest included in recorded investment	744		746
Total Loans	184,424		189,849
Payment Plan Receivable [Member]
Analysis of allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period	144	197
Additions (deductions) [Abstract]
Provision for loan losses	(4)	30
Recoveries credited to allowance	7	0
Loans charged against the allowance	(18)	(21)
Balance at end of period	129	206
Allowance for loan losses [Abstract]
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	129		144
Total ending allowance balance	129		144
Loans [Abstract]
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	78,311		84,692
Total loans recorded investment	78,311		84,692
Accrued interest included in recorded investment	0		0
Total Loans	78,311		84,692
Unallocated [Member]
Analysis of allowance for loan losses by portfolio segment [Roll Forward]
Balance at beginning of period	7,904	11,473
Additions (deductions) [Abstract]
Provision for loan losses	(651)	(919)
Recoveries credited to allowance	0	0
Loans charged against the allowance	0	0
Balance at end of period	7,253	10,554
Allowance for loan losses [Abstract]
Individually evaluated for impairment	0		0
Collectively evaluated for impairment	7,253		7,904
Total ending allowance balance	$ 7,253		$ 7,904