Quarterly Financial Data (Unaudited) (Details) (USD $)	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Data (Unaudited) [Abstract]
Interest income	$ 28,146,000		$ 26,823,000		$ 26,185,000		$ 25,396,000		$ 24,666,000		$ 24,359,000		$ 23,948,000		$ 23,882,000		$ 106,550,000	$ 96,855,000	$ 88,442,000
Net interest income	25,402,000		24,117,000		23,579,000		22,684,000		22,086,000		21,561,000		20,881,000		20,916,000		95,782,000	85,444,000	76,406,000
Provision for loan and lease losses	6,500,000		8,000,000		9,500,000		5,500,000		7,391,000		5,540,000		4,287,000		5,220,000		29,500,000	22,438,000	21,498,000
Non-interest income	22,334,000		19,602,000		22,362,000		19,132,000		15,626,000		11,233,000		10,449,000		12,290,000		83,430,000	49,598,000	30,525,000
Non-interest expense	29,814,000		28,897,000		27,587,000		24,479,000		23,462,000		21,898,000		21,039,000		21,787,000		110,777,000	88,186,000	72,204,000
Income tax expenses	4,098,000		2,034,000		3,262,000		4,431,000		1,622,000		1,795,000		2,150,000		2,227,000		13,825,000	7,794,000	4,311,000
Net income (loss) available to common shareholders	$ 7,324,000		$ 4,788,000		$ 5,592,000		$ 7,406,000		$ 5,237,000		$ 3,561,000		$ 3,854,000		$ 3,972,000		$ 25,110,000	$ 16,624,000	$ 8,918,000
Net income per share - basic (in dollars per share)	$ 0.20	[1]	$ 0.13	[1]	$ 0.15	[1]	$ 0.20	[1]	$ 0.15	[1]	$ 0.11	[1]	$ 0.12	[1]	$ 0.12	[1]	$ 0.67	$ 0.50	$ 0.28
Net income per share - diluted (in dollars per share)	$ 0.19	[1]	$ 0.13	[1]	$ 0.15	[1]	$ 0.20	[1]	$ 0.15	[1]	$ 0.11	[1]	$ 0.12	[1]	$ 0.12	[1]	$ 0.66	$ 0.50	$ 0.28

[1] May not equal annual amounts due to rounding.