Business Combinations - Additional Information (Details) (USD $)	3 Months Ended		6 Months Ended			0 Months Ended	3 Months Ended		6 Months Ended				0 Months Ended	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Aug. 13, 2013 Foster Bankshares Inc	Jun. 30, 2014 Foster Bankshares Inc	Jun. 30, 2013 Foster Bankshares Inc	Jun. 30, 2014 Foster Bankshares Inc	Jun. 30, 2013 Foster Bankshares Inc	Aug. 13, 2013 Foster Bankshares Inc Illinois bank_location	Aug. 13, 2013 Foster Bankshares Inc Virginia bank_location	Feb. 15, 2013 Pacific International Bancorp, Inc.	Jun. 30, 2014 Pacific International Bancorp, Inc.	Jun. 30, 2013 Pacific International Bancorp, Inc.	Jun. 30, 2014 Pacific International Bancorp, Inc.	Jun. 30, 2013 Pacific International Bancorp, Inc.	Jun. 30, 2014 Foster Bankshares, Inc and Pacific International Bancorp, Inc.	Jun. 30, 2013 Foster Bankshares, Inc and Pacific International Bancorp, Inc.	Jun. 30, 2014 Foster Bankshares, Inc and Pacific International Bancorp, Inc.	Jun. 30, 2013 Foster Bankshares, Inc and Pacific International Bancorp, Inc.	Jun. 30, 2014 Exchanged For Shares Of Company Foster Bankshares Inc	Jun. 30, 2014 Purchased For Cash Foster Bankshares Inc	Jun. 30, 2014 Not Redeemed Foster Bankshares Inc
Business Acquisition [Line Items]
Business combination, number of acquired bank branches											8	1
Business acquisition share price						$ 34.6703
Conversion shares per share of acquiree						2.62771
Shares issued									180,300
Number of shares of acquiree																						68,619	58,906	4,475
Cash paid						$ 1,922,000							$ 1,000
Goodwill	105,401,000		105,401,000		105,401,000	15,525,000							118,000
Outstanding principal balances of acquired loans							229,300,000		229,300,000					99,600,000		99,600,000
Carrying amount of acquired loans							187,800,000		187,800,000					84,700,000		84,700,000
Merger and integration expense	$ 50,000	$ 385,000	$ 224,000	$ 1,690,000			$ 50,000	$ 304,000	$ 193,000	$ 358,000				$ 0	$ 81,000	$ 31,000	$ 1,332,000	$ 50,000	$ 385,000	$ 224,000	$ 1,690,000