Loans (Impaired Loans) (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013		Dec. 31, 2012
Financing Receivable, Impaired [Line Items]
Impaired loans, held for sale	$ 0		$ 0
Impaired loans, no individually reviewed for impairment	5,946,000		6,017,000
Impaired loans, individually reviewed, with no impairment	56,985,000		62,282,000
Impaired loans, individually reviewed, with impairment	16,097,000		15,312,000
Total impaired loans, excluding purchased impaired	79,028,000	[1]	83,611,000	[1]
Purchased impaired loans with subsequent deterioration	176,048,000		192,115,000
Purchased impaired loans with no subsequent deterioration	29,836,000		36,277,000
Impaired loan, individually reviewed, with impairment, associated reserves	3,129,000	[1]	1,737,000	[1]
Purchased impaired loans with subsequent deterioration, associated reserves	5,373,000		5,373,000
Impaired financing receivable, including deteriorated loans purchased, related allowance	8,502,000		7,110,000
Imparied financing receivable, simple average balance	76,319,000		94,754,000
Restructured loans	18,200,000		20,800,000
Performing [Member]
Financing Receivable, Impaired [Line Items]
Restructured loans	$ 3,600,000		$ 4,500,000

[1] March 31, 2013 December 31, 2012(dollars in thousands) BalanceAssociated Reserves BalanceAssociated ReservesImpaired loans, held for sale $—$— $—$—Impaired loans, not individually reviewed for impairment 5,946— 6,017—Impaired loans, individually reviewed, with no impairment 56,985— 62,282—Impaired loans, individually reviewed, with impairment 16,0973,129 15,3121,737Total impaired loans, excluding purchased impaired * $79,028$3,129 $83,611$1,737 Purchased impaired loans with subsequent deterioration $176,0485,373 $192,1155,373Purchased impaired loans with no subsequent deterioration $29,836— $36,277—Total Reserves $8,502 $7,110 Average impaired loans calculated using a simple average $76,319 $94,754