Parent Company Financial Statements (Condensed Statements of Income and Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
INCOME
Net Gains on Securities									$ 725	$ 1,481	$ 2,429
EXPENSE
Salaries and Employee Benefits									35,042	32,710	31,482
Professional Fees									2,661	2,294	2,577
Interest Expense									6,068	6,047	7,155
INCOME BEFORE INCOME TAXES AND EQUITY IN UNDISTRIBUTED INCOME OF SUBSIDIARIES									41,670	40,413	36,877
Income Tax Benefit									(11,606)	(12,069)	(11,464)
NET INCOME	$ 7,712	$ 7,721	$ 7,325	$ 7,306	$ 7,644	$ 7,708	$ 6,687	$ 6,305	30,064	28,344	25,413
Other Comprehensive Income:
COMPREHENSIVE INCOME									30,986	36,497	9,799
Parent Company
INCOME
Interest Income									30	27	31
Net Gains on Securities									0	0	343
Other Income									21	25	75
Total Income									17,455	20,052	15,949
EXPENSE
Salaries and Employee Benefits									500	462	824
Professional Fees									667	316	485
Occupancy and Equipment Expense									8	7	7
Interest Expense									491	580	1,246
Other Expenses									729	632	615
Total Expenses									2,395	1,997	3,177
INCOME BEFORE INCOME TAXES AND EQUITY IN UNDISTRIBUTED INCOME OF SUBSIDIARIES									15,060	18,055	12,772
Income Tax Benefit									893	791	1,235
INCOME BEFORE EQUITY IN UNDISTRIBUTED INCOME OF SUBSIDIARIES									15,953	18,846	14,007
Equity in Undistributed Income of Subsidiaries									14,111	9,498	11,406
NET INCOME									30,064	28,344	25,413
Other Comprehensive Income:
Changes in Unrealized Gain (Loss) on Securities, Available-for-Sale									932	8,189	(15,874)
Changes in Unrecognized Amounts in Pension, Net									0	0	231
Changes in Unrecognized Loss in Postretirement Benefit Obligation, Net									(10)	(36)	29
COMPREHENSIVE INCOME									30,986	36,497	9,799
Parent Company | Bank
INCOME
Dividends from Subsidiaries									15,900	20,000	14,000
Parent Company | Non Bank
INCOME
Dividends from Subsidiaries									$ 1,504	$ 0	$ 1,500