Investment Securities (Held-to-maturity Securities) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	$ 45,275,000	$ 16,301,000
Gross unrealized gains	1,890,000	492,000
Gross unrealized losses	(41,000)	(88,000)
Held-to-maturity securities, total fair value	47,124,000	16,705,000
Gross realized gains or losses	0	0	0
States and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	3,860,000	3,525,000
Gross unrealized gains	390,000	262,000
Gross unrealized losses	0	0
Held-to-maturity securities, total fair value	4,250,000	3,787,000
Residential mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	33,494,000	12,776,000
Gross unrealized gains	1,107,000	230,000
Gross unrealized losses	(41,000)	(88,000)
Held-to-maturity securities, total fair value	34,560,000	12,918,000
Commercial mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	7,921,000
Gross unrealized gains	393,000
Gross unrealized losses	0
Held-to-maturity securities, total fair value	$ 8,314,000