Parent Company Financial Statements, Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets:
Cash on deposit	$ 51,974	$ 56,299
Goodwill	65,490	65,490
Premises and equipment, net	48,188	49,980
Other assets	33,827	27,378
Total assets	3,903,934	3,723,765
Liabilities and shareholders' equity:
Long-term debt	61,341	61,341
Other liabilities	21,431	23,401
Total liabilities	3,428,351	3,275,888
Shareholders' equity	475,583	447,877
Total liabilities and shareholders' equity	3,903,934	3,723,765
Parent Company [Member]
Assets:
Cash on deposit	1,462	995
Investment in and advances to subsidiaries	531,702	503,252
Goodwill	4,973	4,973
Premises and equipment, net	145	207
Other assets	911	1,173
Total assets	539,193	510,600
Liabilities and shareholders' equity:
Long-term debt	61,341	61,341
Other liabilities	2,269	1,382
Total liabilities	63,610	62,723
Shareholders' equity	475,583	447,877
Total liabilities and shareholders' equity	$ 539,193	$ 510,600