Condensed Financial Information of Parent Company (Schedule of Condensed Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets
Cash and due from banks	$ 17,422	$ 11,814
Securities available-for-sale, at fair value	470,523	390,552
Loans, net	676,026	654,691
Premises and equipment, net	21,586	21,086
Other assets	36,369	36,388
Total assets	1,603,209	1,504,839	$ 1,455,506
Liabilities and Shareholders' Equity
Accounts and drafts payable	661,888	642,287
Other liabilities	38,145	32,556
Total liabilities	1,378,121	1,296,804
Total shareholders' equity	225,088	208,035	$ 207,378	$ 200,432
Total liabilities and shareholders' equity	1,603,209	1,504,839
Parent [Member]
Assets
Cash and due from banks	56,462	45,464
Short-term investments	48,324	107,898
Securities available-for-sale, at fair value	470,523	390,552
Loans, net	12,239	47,184
Investments in subsidiaries	113,681	101,824
Premises and equipment, net	20,927	20,375
Other assets	199,865	161,317
Total assets	922,021	874,614
Liabilities and Shareholders' Equity
Accounts and drafts payable	661,342	640,945
Other liabilities	35,533	25,415
Total liabilities	696,875	666,360
Total shareholders' equity	225,146	208,254
Total liabilities and shareholders' equity	$ 922,021	$ 874,614